Most often in June, 21 days.
Highest follower count seen that year: 824.
January
Jan 7 19:00–24:00 Jan 8 01:00–02:00 Jan 10 00:00–01:00, 03:00–06:00 Jan 12 18:00–20:00 Jan 13 04:00–07:00, 16:00–24:00 Jan 14 00:00–04:00 Jan 15 21:00–22:00 Jan 16 12:00–15:00, 17:00–18:00 Jan 20 08:00–14:00 Jan 22 18:00–20:00 Jan 23 18:00–22:00 Jan 24 02:00–05:00 Jan 25 16:00–23:00
February
Feb 10 05:00–08:00 Feb 11 19:00–22:00 Feb 12 22:00–24:00 Feb 14 20:00–24:00 Feb 15 02:00–03:00 Feb 18 22:00–24:00 Feb 19 00:00–14:00 Feb 20 21:00–24:00 Feb 21 00:00–03:00, 20:00–23:00 Feb 23 18:00–21:00
March
Mar 3 16:00–23:00 Mar 7 15:00–24:00 Mar 8 00:00–01:00 Mar 10 04:00–07:00 Mar 11 16:00–24:00 Mar 12 00:00–02:00 Mar 15 01:00–06:00 Mar 17 18:00–23:00 Mar 18 00:00–04:00 Mar 19 16:00–19:00, 21:00–24:00 Mar 20 00:00–03:00 Mar 22 06:00–16:00 Mar 23 16:00–24:00 Mar 25 16:00–19:00 Mar 26 06:00–09:00 Mar 28 23:00–24:00 Mar 29 00:00–03:00, 06:00–09:00, 12:00–18:00 Mar 30 02:00–13:00, 16:00–17:00 Mar 31 05:00–06:00, 10:00–12:00
April
Apr 1 19:00–24:00 Apr 2 10:00–18:00 Apr 6 21:00–22:00 Apr 7 15:00–24:00 Apr 8 04:00–05:00, 21:00–24:00 Apr 9 00:00–04:00, 17:00–18:00, 21:00–23:00 Apr 10 00:00–03:00, 06:00–08:00 Apr 12 16:00–24:00 Apr 13 00:00–03:00, 18:00–23:00 Apr 16 07:00–09:00, 13:00–18:00, 21:00–23:00 Apr 18 16:00–23:00 Apr 21 22:00–24:00 Apr 22 00:00–01:00 Apr 24 17:00–24:00 Apr 25 00:00–01:00, 07:00–11:00, 20:00–24:00 Apr 26 00:00–01:00 Apr 29 05:00–11:00 Apr 30 12:00–13:00, 15:00–24:00
May
May 3 05:00–11:00 May 5 16:00–22:00 May 10 18:00–24:00 May 13 08:00–15:00, 22:00–24:00 May 14 00:00–01:00 May 16 13:00–15:00 May 18 18:00–21:00 May 22 08:00–11:00, 23:00–24:00 May 23 00:00–02:00 May 24 16:00–19:00 May 25 00:00–01:00, 08:00–12:00 May 27 22:00–24:00 May 29 05:00–08:00, 19:00–23:00 May 31 11:00–12:00, 14:00–21:00
June
Jun 2 02:00–09:00 Jun 3 13:00–17:00, 22:00–24:00 Jun 4 00:00–01:00 Jun 8 12:00–13:00, 16:00–19:00 Jun 11 03:00–07:00, 19:00–24:00 Jun 12 13:00–15:00 Jun 13 03:00–04:00 Jun 14 06:00–07:00, 18:00–20:00 Jun 15 20:00–23:00 Jun 16 00:00–01:00 Jun 17 18:00–24:00 Jun 18 00:00–02:00, 19:00–21:00 Jun 19 10:00–14:00 Jun 20 16:00–19:00 Jun 23 03:00–06:00 Jun 24 11:00–13:00, 15:00–17:00 Jun 25 13:00–15:00 Jun 26 01:00–04:00 Jun 27 10:00–12:00 Jun 29 17:00–22:00 Jun 30 00:00–01:00, 14:00–17:00
July
Jul 1 18:00–19:00, 23:00–24:00 Jul 2 00:00–02:00 Jul 3 17:00–18:00 Jul 4 03:00–12:00 Jul 5 18:00–24:00 Jul 6 00:00–04:00 Jul 9 17:00–21:00 Jul 13 04:00–10:00 Jul 15 23:00–24:00 Jul 16 00:00–09:00 Jul 17 02:00–03:00 Jul 18 16:00–20:00 Jul 19 08:00–11:00 Jul 21 20:00–24:00 Jul 22 00:00–01:00 Jul 29 03:00–07:00, 17:00–19:00 Jul 30 18:00–22:00
August
Aug 15 12:00–17:00 Aug 21 18:00–20:00 Aug 26 10:00–14:00
September
Sep 11 23:00–24:00 Sep 12 00:00–01:00, 04:00–05:00, 08:00–11:00 Sep 13 02:00–05:00, 12:00–16:00, 18:00–21:00 Sep 19 06:00–07:00 Sep 20 06:00–07:00 Sep 22 00:00–05:00, 08:00–12:00 Sep 23 18:00–21:00 Sep 24 07:00–09:00, 14:00–15:00, 18:00–19:00 Sep 29 14:00–15:00 Sep 30 11:00–13:00
October
Oct 2 11:00–12:00 Oct 5 17:00–21:00 Oct 6 07:00–10:00, 12:00–23:00 Oct 7 02:00–04:00 Oct 10 09:00–11:00, 17:00–24:00 Oct 11 00:00–07:00 Oct 12 17:00–18:00, 20:00–23:00 Oct 13 03:00–06:00 Oct 14 09:00–19:00 Oct 15 00:00–03:00 Oct 16 14:00–19:00, 21:00–22:00 Oct 20 23:00–24:00 Oct 21 00:00–02:00 Oct 22 13:00–14:00, 20:00–24:00 Oct 23 00:00–02:00, 08:00–09:00, 19:00–20:00 Oct 26 15:00–19:00 Oct 27 02:00–12:00 Oct 29 13:00–16:00 Oct 31 16:00–24:00
November
Nov 1 00:00–01:00, 05:00–08:00 Nov 2 14:00–18:00 Nov 3 03:00–07:00 Nov 5 11:00–13:00 Nov 6 03:00–08:00 Nov 8 18:00–24:00 Nov 10 01:00–04:00 Nov 11 20:00–24:00 Nov 12 00:00–01:00, 08:00–09:00 Nov 17 23:00–24:00 Nov 21 00:00–07:00, 13:00–17:00 Nov 22 08:00–11:00 Nov 25 17:00–18:00 Nov 26 07:00–13:00, 17:00–23:00 Nov 27 19:00–21:00 Nov 28 00:00–05:00, 10:00–11:00, 16:00–17:00 Nov 29 21:00–24:00 Nov 30 01:00–02:00, 04:00–11:00, 13:00–16:00, 20:00–24:00
December
Dec 1 00:00–06:00 Dec 2 14:00–18:00 Dec 3 00:00–02:00, 23:00–24:00 Dec 4 08:00–10:00, 17:00–20:00, 22:00–24:00 Dec 5 00:00–01:00, 13:00–18:00 Dec 6 04:00–05:00, 15:00–23:00 Dec 7 08:00–10:00 Dec 9 17:00–18:00 Dec 10 01:00–06:00 Dec 11 02:00–03:00, 07:00–08:00 Dec 13 11:00–13:00, 16:00–23:00 Dec 14 10:00–13:00 Dec 18 11:00–19:00 Dec 19 19:00–22:00 Dec 20 06:00–08:00, 17:00–24:00 Dec 21 00:00–08:00, 13:00–19:00 Dec 23 00:00–11:00