Most often in September, 27 days.
Highest follower count seen that year: 23,700.
January
Jan 5 15:00–20:00 Jan 7 22:00–23:00 Jan 8 00:00–01:00, 21:00–24:00 Jan 9 00:00–01:00 Jan 14 12:00–13:00 Jan 16 20:00–24:00 Jan 17 00:00–01:00, 20:00–24:00 Jan 18 00:00–01:00, 21:00–24:00 Jan 19 00:00–01:00 Jan 20 22:00–24:00 Jan 21 00:00–01:00, 16:00–19:00, 21:00–24:00 Jan 22 19:00–24:00 Jan 24 21:00–24:00 Jan 25 22:00–24:00 Jan 26 00:00–03:00 Jan 28 16:00–19:00, 23:00–24:00 Jan 29 00:00–01:00 Jan 30 13:00–16:00, 21:00–23:00
February
Feb 1 21:00–24:00 Feb 2 00:00–01:00 Feb 3 12:00–16:00 Feb 4 12:00–15:00 Feb 5 12:00–16:00, 22:00–24:00 Feb 6 12:00–16:00, 21:00–24:00 Feb 7 00:00–01:00, 12:00–16:00, 23:00–24:00 Feb 8 00:00–01:00, 16:00–20:00, 22:00–24:00 Feb 10 12:00–16:00 Feb 11 12:00–16:00 Feb 12 13:00–16:00, 23:00–24:00 Feb 13 00:00–01:00, 21:00–24:00 Feb 14 00:00–01:00, 23:00–24:00 Feb 15 00:00–01:00 Feb 17 12:00–16:00 Feb 18 22:00–24:00 Feb 19 12:00–15:00, 23:00–24:00 Feb 20 00:00–01:00, 22:00–24:00 Feb 21 00:00–01:00 Feb 22 22:00–24:00 Feb 24 12:00–15:00 Feb 26 12:00–16:00, 22:00–24:00 Feb 27 00:00–01:00, 12:00–16:00, 22:00–24:00 Feb 28 16:00–18:00
March
Mar 4 13:00–16:00, 22:00–23:00 Mar 6 00:00–01:00 Mar 7 12:00–14:00 Mar 12 13:00–16:00, 22:00–23:00 Mar 13 03:00–04:00, 13:00–16:00, 22:00–24:00 Mar 14 21:00–24:00 Mar 15 00:00–01:00, 21:00–24:00 Mar 17 12:00–16:00, 21:00–24:00 Mar 18 12:00–15:00, 22:00–24:00 Mar 19 00:00–01:00, 12:00–15:00 Mar 20 12:00–15:00, 21:00–24:00 Mar 21 14:00–18:00, 22:00–23:00 Mar 22 22:00–24:00 Mar 23 20:00–24:00 Mar 25 12:00–16:00, 23:00–24:00 Mar 26 00:00–01:00, 14:00–17:00, 22:00–24:00 Mar 27 00:00–01:00, 21:00–23:00 Mar 29 21:00–24:00 Mar 30 00:00–01:00, 22:00–24:00 Mar 31 00:00–01:00, 13:00–15:00, 22:00–24:00
April
Apr 1 00:00–01:00, 13:00–15:00 Apr 2 14:00–16:00, 21:00–24:00 Apr 3 00:00–01:00, 13:00–16:00, 22:00–23:00 Apr 4 21:00–24:00 Apr 5 00:00–01:00 Apr 7 17:00–19:00, 22:00–24:00 Apr 8 00:00–01:00, 13:00–14:00, 22:00–24:00 Apr 9 22:00–24:00 Apr 11 13:00–15:00, 22:00–24:00 Apr 13 21:00–22:00 Apr 14 17:00–23:00 Apr 15 16:00–20:00, 22:00–23:00 Apr 17 19:00–22:00 Apr 20 22:00–24:00 Apr 21 15:00–19:00, 22:00–24:00 Apr 23 16:00–19:00, 21:00–24:00 Apr 24 12:00–15:00, 22:00–24:00 Apr 25 16:00–19:00 Apr 27 23:00–24:00 Apr 28 00:00–02:00, 21:00–24:00 Apr 29 00:00–01:00, 13:00–16:00, 23:00–24:00 Apr 30 00:00–01:00, 13:00–16:00, 22:00–24:00
May
May 1 00:00–01:00, 22:00–24:00 May 2 00:00–01:00 May 3 21:00–24:00 May 4 12:00–14:00, 20:00–23:00 May 5 16:00–19:00 May 6 21:00–23:00 May 7 13:00–15:00, 22:00–24:00 May 8 22:00–24:00 May 9 00:00–01:00 May 10 23:00–24:00 May 11 00:00–02:00 May 13 13:00–18:00, 22:00–24:00 May 14 13:00–18:00, 22:00–23:00 May 15 13:00–17:00, 21:00–24:00 May 19 16:00–19:00, 21:00–24:00 May 20 13:00–16:00 May 21 14:00–16:00, 23:00–24:00 May 22 00:00–01:00, 22:00–24:00 May 23 23:00–24:00 May 24 00:00–01:00 May 25 20:00–23:00 May 26 22:00–24:00 May 27 00:00–01:00, 13:00–16:00, 22:00–24:00 May 28 00:00–01:00, 13:00–15:00, 21:00–24:00 May 29 00:00–01:00, 14:00–18:00, 23:00–24:00 May 30 00:00–01:00 May 31 19:00–21:00
June
Jun 1 21:00–24:00 Jun 2 00:00–01:00 Jun 3 13:00–16:00, 22:00–24:00 Jun 4 13:00–15:00, 22:00–24:00 Jun 5 14:00–15:00 Jun 6 21:00–24:00 Jun 8 21:00–24:00 Jun 9 00:00–01:00, 22:00–23:00 Jun 10 22:00–24:00 Jun 11 00:00–01:00, 21:00–24:00 Jun 12 22:00–24:00 Jun 13 00:00–01:00, 22:00–24:00 Jun 15 14:00–17:00, 22:00–24:00 Jun 16 22:00–24:00 Jun 17 00:00–01:00 Jun 19 12:00–14:00 Jun 20 20:00–24:00 Jun 21 00:00–01:00, 22:00–24:00 Jun 22 00:00–01:00, 20:00–24:00 Jun 23 00:00–01:00, 14:00–18:00 Jun 24 22:00–24:00 Jun 25 00:00–01:00, 12:00–14:00, 22:00–24:00 Jun 26 00:00–02:00, 14:00–16:00, 20:00–24:00 Jun 27 00:00–01:00 Jun 29 21:00–24:00 Jun 30 00:00–01:00, 20:00–23:00
July
Jul 3 23:00–24:00 Jul 4 00:00–01:00, 22:00–24:00 Jul 5 00:00–01:00 Jul 6 00:00–01:00, 12:00–16:00 Jul 8 21:00–23:00 Jul 9 22:00–24:00 Jul 10 23:00–24:00 Jul 11 00:00–01:00, 16:00–17:00 Jul 12 21:00–23:00 Jul 13 17:00–19:00, 21:00–24:00 Jul 14 22:00–24:00 Jul 15 00:00–02:00, 14:00–15:00, 21:00–24:00 Jul 16 00:00–01:00, 23:00–24:00 Jul 17 00:00–01:00 Jul 19 21:00–24:00 Jul 20 12:00–15:00 Jul 21 21:00–24:00 Jul 22 00:00–01:00, 13:00–15:00, 22:00–24:00 Jul 26 21:00–24:00 Jul 27 19:00–21:00 Jul 28 21:00–24:00 Jul 29 00:00–01:00, 22:00–24:00 Jul 30 00:00–01:00, 22:00–24:00 Jul 31 00:00–01:00, 16:00–18:00, 22:00–24:00
August
Aug 2 16:00–19:00 Aug 4 22:00–24:00 Aug 6 23:00–24:00 Aug 7 00:00–01:00, 16:00–19:00 Aug 8 21:00–24:00 Aug 9 00:00–01:00, 22:00–24:00 Aug 10 00:00–01:00 Aug 11 17:00–22:00 Aug 12 13:00–17:00, 22:00–24:00 Aug 13 00:00–01:00, 16:00–19:00, 22:00–24:00 Aug 14 13:00–16:00 Aug 15 16:00–24:00 Aug 16 21:00–24:00 Aug 17 00:00–01:00 Aug 18 20:00–24:00 Aug 19 12:00–16:00, 22:00–24:00 Aug 20 13:00–16:00 Aug 21 00:00–01:00, 13:00–15:00 Aug 22 23:00–24:00 Aug 23 00:00–01:00 Aug 24 13:00–15:00 Aug 26 00:00–01:00, 23:00–24:00 Aug 27 00:00–01:00 Aug 28 21:00–24:00 Aug 29 16:00–18:00, 22:00–24:00 Aug 30 00:00–01:00, 17:00–19:00 Aug 31 15:00–19:00
September
Sep 2 14:00–16:00, 22:00–24:00 Sep 3 00:00–01:00, 13:00–15:00, 23:00–24:00 Sep 4 00:00–01:00, 22:00–24:00 Sep 5 00:00–01:00, 16:00–19:00 Sep 6 23:00–24:00 Sep 8 01:00–04:00, 17:00–19:00 Sep 9 14:00–19:00 Sep 10 12:00–19:00, 21:00–24:00 Sep 11 22:00–24:00 Sep 12 00:00–01:00, 15:00–18:00 Sep 13 13:00–16:00 Sep 14 20:00–24:00 Sep 15 23:00–24:00 Sep 16 00:00–01:00, 22:00–23:00 Sep 18 22:00–24:00 Sep 19 00:00–01:00, 16:00–17:00, 22:00–24:00 Sep 20 00:00–01:00, 19:00–24:00 Sep 21 00:00–03:00 Sep 22 15:00–19:00, 21:00–24:00 Sep 23 00:00–01:00, 21:00–24:00 Sep 24 00:00–01:00, 12:00–16:00 Sep 25 16:00–19:00 Sep 26 12:00–17:00 Sep 27 22:00–24:00 Sep 28 00:00–01:00 Sep 29 12:00–18:00 Sep 30 15:00–18:00
October
Oct 2 23:00–24:00 Oct 3 16:00–19:00, 22:00–24:00 Oct 4 22:00–24:00 Oct 5 20:00–24:00 Oct 6 00:00–02:00, 22:00–24:00 Oct 7 00:00–01:00 Oct 8 17:00–20:00 Oct 9 22:00–24:00 Oct 10 00:00–01:00 Oct 11 20:00–22:00 Oct 12 13:00–17:00 Oct 13 18:00–20:00 Oct 14 12:00–16:00, 22:00–24:00 Oct 15 00:00–01:00, 22:00–24:00 Oct 18 21:00–24:00 Oct 19 13:00–16:00 Oct 21 18:00–19:00, 22:00–24:00 Oct 22 17:00–18:00, 22:00–24:00 Oct 23 22:00–24:00 Oct 24 17:00–18:00, 21:00–23:00 Oct 25 22:00–24:00 Oct 26 00:00–01:00, 21:00–24:00 Oct 30 15:00–17:00 Oct 31 00:00–02:00, 16:00–20:00
November
Nov 2 20:00–22:00 Nov 4 13:00–15:00, 22:00–24:00 Nov 5 00:00–01:00 Nov 6 16:00–18:00, 21:00–24:00 Nov 7 00:00–01:00, 16:00–19:00, 21:00–24:00 Nov 9 00:00–02:00, 22:00–24:00 Nov 10 00:00–01:00, 23:00–24:00 Nov 11 00:00–01:00, 22:00–24:00 Nov 12 00:00–01:00 Nov 13 22:00–24:00 Nov 14 22:00–23:00 Nov 15 22:00–24:00 Nov 16 22:00–24:00 Nov 17 00:00–01:00 Nov 18 22:00–24:00 Nov 19 00:00–01:00 Nov 20 00:00–05:00, 23:00–24:00 Nov 21 00:00–01:00, 17:00–19:00 Nov 26 21:00–24:00 Nov 29 13:00–15:00, 22:00–24:00 Nov 30 00:00–01:00, 21:00–24:00
December
Dec 1 00:00–01:00, 14:00–15:00, 22:00–24:00 Dec 3 17:00–20:00 Dec 4 21:00–24:00 Dec 5 00:00–01:00, 22:00–24:00 Dec 6 19:00–22:00 Dec 7 15:00–18:00 Dec 9 17:00–20:00 Dec 10 18:00–19:00, 23:00–24:00 Dec 11 00:00–01:00 Dec 13 16:00–20:00, 23:00–24:00 Dec 14 00:00–02:00, 14:00–19:00, 22:00–24:00 Dec 15 00:00–01:00, 12:00–16:00, 23:00–24:00 Dec 16 00:00–01:00 Dec 17 18:00–20:00 Dec 19 22:00–24:00 Dec 20 00:00–01:00, 22:00–24:00 Dec 21 00:00–01:00 Dec 23 20:00–24:00 Dec 24 00:00–01:00 Dec 26 17:00–20:00, 23:00–24:00 Dec 27 00:00–01:00, 19:00–22:00 Dec 28 22:00–24:00 Dec 29 00:00–03:00, 13:00–15:00 Dec 30 00:00–03:00, 23:00–24:00 Dec 31 00:00–02:00, 17:00–20:00