Most often in March, 26 days.
Highest follower count seen that year: 58,517.
January
Jan 16 14:00–20:00 Jan 17 14:00–20:00 Jan 18 14:00–20:00 Jan 19 14:00–20:00 Jan 20 14:00–20:00 Jan 23 14:00–20:00 Jan 24 14:00–20:00 Jan 25 14:00–20:00 Jan 26 14:00–21:00 Jan 27 14:00–24:00 Jan 28 00:00–02:00 Jan 30 14:00–20:00 Jan 31 14:00–24:00
February
Feb 1 14:00–20:00 Feb 2 14:00–24:00 Feb 3 00:00–02:00, 14:00–21:00 Feb 7 20:00–24:00 Feb 8 00:00–02:00, 19:00–24:00 Feb 9 00:00–02:00, 14:00–24:00 Feb 10 00:00–01:00, 14:00–24:00 Feb 11 00:00–02:00 Feb 13 20:00–24:00 Feb 14 00:00–07:00 Feb 15 15:00–24:00 Feb 16 00:00–02:00, 16:00–24:00 Feb 17 00:00–02:00, 17:00–24:00 Feb 18 00:00–02:00 Feb 20 20:00–24:00 Feb 21 00:00–02:00, 20:00–24:00 Feb 22 00:00–02:00, 20:00–24:00 Feb 23 00:00–02:00, 16:00–24:00 Feb 24 00:00–03:00, 20:00–24:00 Feb 25 00:00–01:00 Feb 28 20:00–24:00
March
Mar 1 00:00–03:00, 20:00–24:00 Mar 2 00:00–02:00, 14:00–24:00 Mar 3 00:00–01:00, 20:00–24:00 Mar 4 00:00–02:00 Mar 6 20:00–24:00 Mar 7 00:00–02:00, 20:00–24:00 Mar 8 00:00–02:00, 20:00–24:00 Mar 9 00:00–02:00, 20:00–24:00 Mar 10 00:00–02:00, 20:00–24:00 Mar 11 00:00–03:00 Mar 13 20:00–24:00 Mar 14 00:00–02:00, 14:00–24:00 Mar 15 00:00–02:00, 14:00–24:00 Mar 16 00:00–02:00, 20:00–24:00 Mar 17 00:00–02:00, 20:00–24:00 Mar 18 00:00–01:00 Mar 20 20:00–24:00 Mar 21 00:00–02:00, 20:00–24:00 Mar 22 00:00–05:00, 20:00–24:00 Mar 23 00:00–06:00, 20:00–24:00 Mar 24 00:00–04:00, 20:00–24:00 Mar 25 00:00–02:00 Mar 28 20:00–24:00 Mar 29 00:00–02:00, 20:00–24:00 Mar 30 00:00–03:00, 20:00–24:00 Mar 31 00:00–04:00, 20:00–24:00
April
Apr 1 00:00–02:00 Apr 4 01:00–02:00, 20:00–24:00 Apr 5 00:00–04:00, 20:00–24:00 Apr 6 00:00–06:00, 20:00–24:00 Apr 7 00:00–03:00, 20:00–24:00 Apr 8 00:00–02:00 Apr 10 20:00–24:00 Apr 11 01:00–02:00, 18:00–24:00 Apr 12 00:00–03:00, 20:00–24:00 Apr 13 00:00–03:00, 20:00–24:00 Apr 14 00:00–06:00, 20:00–24:00 Apr 15 00:00–03:00 Apr 17 20:00–24:00 Apr 18 00:00–02:00 Apr 19 20:00–24:00 Apr 20 00:00–01:00, 20:00–24:00 Apr 21 00:00–03:00, 20:00–24:00 Apr 22 00:00–02:00 Apr 24 20:00–24:00 Apr 25 00:00–03:00, 20:00–24:00 Apr 26 00:00–02:00, 20:00–23:00 Apr 27 00:00–04:00, 20:00–24:00 Apr 28 00:00–02:00, 20:00–24:00 Apr 29 00:00–03:00
May
May 1 20:00–24:00 May 2 00:00–01:00, 20:00–24:00 May 3 00:00–02:00, 21:00–24:00 May 4 00:00–03:00, 20:00–24:00 May 5 00:00–02:00, 20:00–24:00 May 6 00:00–01:00 May 8 20:00–24:00 May 9 01:00–02:00, 20:00–24:00 May 10 00:00–06:00, 20:00–24:00 May 11 00:00–02:00, 21:00–23:00 May 12 00:00–04:00 May 15 20:00–24:00 May 16 00:00–02:00, 20:00–24:00 May 17 00:00–08:00, 20:00–24:00 May 18 00:00–02:00, 20:00–24:00 May 19 00:00–05:00, 20:00–22:00 May 22 20:00–24:00 May 23 00:00–05:00, 21:00–24:00 May 24 00:00–04:00, 20:00–24:00 May 25 00:00–03:00, 20:00–24:00 May 26 00:00–04:00, 20:00–24:00 May 27 00:00–03:00 May 29 20:00–24:00 May 30 00:00–03:00, 20:00–24:00 May 31 00:00–06:00, 20:00–24:00
June
Jun 1 00:00–03:00, 20:00–24:00 Jun 2 00:00–03:00, 20:00–24:00 Jun 3 00:00–02:00 Jun 5 20:00–24:00 Jun 6 00:00–03:00, 21:00–24:00 Jun 7 00:00–02:00, 21:00–24:00 Jun 8 00:00–02:00, 20:00–24:00 Jun 9 00:00–02:00, 20:00–24:00 Jun 10 00:00–02:00 Jun 12 14:00–19:00 Jun 15 01:00–06:00, 20:00–24:00 Jun 16 00:00–02:00, 18:00–24:00 Jun 17 00:00–02:00 Jun 19 20:00–24:00 Jun 20 00:00–04:00, 20:00–24:00 Jun 21 00:00–05:00, 20:00–24:00 Jun 22 00:00–04:00, 20:00–24:00 Jun 23 00:00–01:00, 21:00–24:00 Jun 24 00:00–03:00 Jun 26 20:00–24:00 Jun 27 00:00–04:00, 20:00–24:00 Jun 28 00:00–02:00, 20:00–24:00 Jun 29 00:00–05:00, 20:00–24:00 Jun 30 00:00–02:00, 20:00–24:00
July
Jul 1 00:00–03:00, 20:00–24:00 Jul 2 00:00–02:00, 20:00–24:00 Jul 3 00:00–02:00, 20:00–24:00 Jul 4 00:00–02:00 Jul 6 20:00–24:00 Jul 7 00:00–02:00, 20:00–24:00 Jul 8 00:00–02:00, 20:00–24:00 Jul 9 00:00–02:00 Jul 11 20:00–22:00 Jul 12 20:00–24:00 Jul 13 00:00–03:00, 21:00–24:00 Jul 14 00:00–02:00, 20:00–24:00 Jul 15 00:00–02:00, 20:00–24:00 Jul 17 20:00–24:00 Jul 18 00:00–03:00, 21:00–24:00 Jul 19 00:00–02:00, 20:00–24:00 Jul 20 00:00–02:00, 21:00–24:00 Jul 21 00:00–03:00, 20:00–24:00 Jul 22 00:00–02:00 Jul 23 19:00–24:00 Jul 24 00:00–01:00