Most often in March, 27 days.
Highest follower count seen that year: 19,756.
January
Jan 4 14:00–20:00 Jan 5 17:00–23:00 Jan 6 11:00–19:00 Jan 13 13:00–21:00 Jan 14 15:00–22:00 Jan 15 13:00–22:00 Jan 16 13:00–18:00 Jan 17 13:00–21:00 Jan 19 13:00–21:00 Jan 20 13:00–21:00 Jan 21 13:00–19:00 Jan 22 16:00–23:00 Jan 23 13:00–22:00 Jan 24 14:00–15:00, 17:00–23:00 Jan 26 12:00–19:00 Jan 27 11:00–20:00 Jan 28 12:00–22:00 Jan 29 13:00–21:00 Jan 30 13:00–15:00, 21:00–24:00 Jan 31 00:00–03:00, 10:00–11:00, 14:00–22:00
February
Feb 3 14:00–19:00 Feb 4 13:00–18:00 Feb 5 10:00–19:00 Feb 6 14:00–21:00 Feb 7 16:00–23:00 Feb 9 18:00–23:00 Feb 10 13:00–22:00 Feb 11 13:00–23:00 Feb 12 13:00–22:00 Feb 13 13:00–21:00 Feb 14 11:00–21:00 Feb 15 13:00–20:00 Feb 18 04:00–17:00 Feb 19 12:00–20:00 Feb 20 12:00–21:00 Feb 21 12:00–22:00 Feb 22 13:00–19:00 Feb 23 14:00–20:00 Feb 24 11:00–21:00 Feb 25 11:00–21:00 Feb 26 09:00–20:00 Feb 27 10:00–21:00 Feb 28 10:00–21:00
March
Mar 1 13:00–19:00 Mar 3 12:00–21:00 Mar 4 13:00–20:00 Mar 5 12:00–21:00 Mar 6 14:00–21:00 Mar 7 19:00–20:00 Mar 8 11:00–16:00 Mar 9 13:00–18:00 Mar 10 12:00–20:00 Mar 12 11:00–21:00 Mar 13 11:00–20:00 Mar 14 10:00–20:00 Mar 15 11:00–20:00 Mar 16 13:00–15:00 Mar 19 11:00–21:00 Mar 20 12:00–21:00 Mar 21 12:00–20:00 Mar 22 13:00–17:00 Mar 23 13:00–17:00 Mar 24 13:00–18:00 Mar 25 13:00–19:00 Mar 26 12:00–20:00 Mar 27 13:00–21:00 Mar 28 13:00–21:00 Mar 29 12:00–18:00 Mar 30 12:00–19:00 Mar 31 12:00–21:00
April
Apr 2 11:00–21:00 Apr 3 11:00–18:00 Apr 4 11:00–21:00 Apr 5 11:00–16:00 Apr 7 11:00–21:00 Apr 8 11:00–18:00 Apr 9 11:00–18:00 Apr 10 11:00–21:00 Apr 11 10:00–21:00 Apr 12 12:00–17:00 Apr 13 11:00–18:00 Apr 14 11:00–21:00 Apr 15 11:00–21:00 Apr 16 11:00–20:00 Apr 20 11:00–17:00 Apr 21 12:00–21:00 Apr 22 11:00–20:00 Apr 23 11:00–19:00 Apr 24 11:00–21:00 Apr 25 11:00–22:00 Apr 26 11:00–17:00 Apr 27 13:00–17:00, 19:00–20:00 Apr 28 11:00–14:00, 19:00–21:00 Apr 29 11:00–21:00 Apr 30 11:00–21:00
May
May 2 11:00–20:00 May 3 12:00–18:00 May 5 11:00–14:00, 16:00–21:00 May 6 11:00–20:00 May 7 11:00–19:00 May 8 12:00–21:00 May 9 11:00–21:00 May 11 14:00–19:00 May 12 08:00–18:00 May 13 04:00–05:00, 09:00–18:00 May 14 02:00–06:00, 09:00–18:00 May 15 02:00–03:00, 05:00–06:00, 09:00–18:00 May 18 13:00–16:00 May 19 11:00–21:00 May 20 11:00–18:00 May 21 10:00–19:00 May 22 11:00–18:00 May 23 12:00–20:00 May 25 11:00–19:00 May 26 11:00–20:00 May 27 10:00–20:00 May 28 11:00–20:00 May 29 02:00–06:00, 09:00–17:00 May 30 05:00–19:00
June
Jun 2 12:00–19:00 Jun 3 10:00–17:00 Jun 4 11:00–20:00 Jun 5 11:00–21:00 Jun 6 12:00–21:00 Jun 7 13:00–18:00 Jun 9 11:00–20:00 Jun 10 03:00–06:00, 09:00–16:00 Jun 11 15:00–21:00 Jun 12 11:00–19:00 Jun 13 12:00–20:00 Jun 15 11:00–15:00, 17:00–20:00 Jun 17 02:00–20:00 Jun 18 12:00–20:00 Jun 19 12:00–20:00 Jun 20 13:00–20:00 Jun 21 12:00–16:00 Jun 22 13:00–20:00 Jun 23 11:00–20:00 Jun 24 12:00–20:00 Jun 25 03:00–07:00, 09:00–14:00 Jun 26 14:00–20:00 Jun 27 12:00–17:00 Jun 28 14:00–18:00
July
Jul 9 03:00–15:00 Jul 10 03:00–06:00, 08:00–16:00 Jul 13 12:00–21:00 Jul 14 12:00–18:00 Jul 15 04:00–07:00, 09:00–15:00 Jul 16 11:00–21:00 Jul 17 12:00–19:00 Jul 18 12:00–16:00 Jul 19 12:00–17:00 Jul 20 13:00–18:00 Jul 21 12:00–20:00 Jul 23 11:00–20:00 Jul 24 12:00–18:00 Jul 25 12:00–21:00 Jul 26 12:00–17:00 Jul 27 12:00–18:00 Jul 28 12:00–22:00 Jul 29 12:00–20:00 Jul 30 18:00–23:00 Jul 31 11:00–13:00, 15:00–21:00
August
Aug 1 12:00–21:00 Aug 2 12:00–17:00 Aug 3 13:00–19:00 Aug 7 04:00–07:00, 09:00–20:00 Aug 8 12:00–15:00, 17:00–21:00 Aug 9 13:00–17:00 Aug 10 13:00–20:00 Aug 11 12:00–17:00 Aug 12 11:00–20:00 Aug 13 12:00–20:00 Aug 14 11:00–20:00 Aug 15 11:00–23:00 Aug 16 13:00–18:00 Aug 19 12:00–18:00 Aug 20 03:00–07:00, 09:00–20:00 Aug 21 13:00–19:00 Aug 22 13:00–24:00 Aug 24 12:00–20:00 Aug 25 05:00–07:00, 14:00–19:00 Aug 26 12:00–20:00 Aug 27 12:00–17:00 Aug 28 12:00–21:00 Aug 29 15:00–20:00 Aug 30 13:00–18:00 Aug 31 12:00–18:00
September
Sep 2 13:00–20:00 Sep 3 07:00–20:00 Sep 5 12:00–21:00 Sep 6 13:00–17:00 Sep 7 13:00–20:00 Sep 8 12:00–21:00 Sep 9 13:00–23:00 Sep 10 07:00–11:00, 13:00–18:00 Sep 11 11:00–17:00 Sep 12 12:00–20:00 Sep 14 13:00–21:00 Sep 15 12:00–17:00, 19:00–22:00