Most often in March, 24 days.
Highest follower count seen that year: 30,312.
January
Jan 5 18:00–24:00 Jan 6 00:00–01:00, 12:00–19:00 Jan 7 12:00–20:00 Jan 8 12:00–20:00 Jan 9 11:00–19:00 Jan 10 12:00–21:00 Jan 11 17:00–24:00 Jan 12 18:00–24:00 Jan 13 00:00–02:00, 08:00–21:00 Jan 15 12:00–24:00 Jan 16 00:00–03:00, 11:00–18:00 Jan 17 12:00–20:00 Jan 20 12:00–20:00 Jan 21 11:00–21:00 Jan 22 12:00–20:00 Jan 23 12:00–21:00 Jan 24 14:00–19:00 Jan 26 16:00–23:00 Jan 27 12:00–20:00 Jan 28 18:00–24:00 Jan 29 00:00–01:00, 11:00–13:00, 15:00–21:00 Jan 30 12:00–20:00 Jan 31 17:00–24:00
February
Feb 3 12:00–20:00 Feb 5 11:00–17:00 Feb 6 12:00–21:00 Feb 8 12:00–16:00 Feb 11 13:00–24:00 Feb 12 00:00–01:00, 12:00–19:00 Feb 14 00:00–03:00, 17:00–24:00 Feb 15 09:00–24:00 Feb 16 00:00–04:00, 11:00–18:00 Feb 22 14:00–24:00 Feb 23 00:00–04:00, 11:00–21:00 Feb 24 16:00–20:00
March
Mar 2 12:00–24:00 Mar 3 00:00–01:00, 12:00–19:00 Mar 4 12:00–19:00 Mar 5 12:00–16:00 Mar 7 13:00–19:00 Mar 9 12:00–24:00 Mar 10 00:00–02:00 Mar 11 12:00–19:00 Mar 12 12:00–19:00 Mar 13 12:00–19:00 Mar 14 04:00–07:00, 10:00–18:00 Mar 15 14:00–19:00 Mar 18 12:00–15:00 Mar 20 12:00–19:00 Mar 21 11:00–19:00 Mar 22 16:00–24:00 Mar 23 00:00–03:00, 12:00–19:00 Mar 25 11:00–22:00 Mar 26 00:00–03:00, 08:00–18:00 Mar 27 16:00–24:00 Mar 28 12:00–20:00 Mar 29 12:00–15:00 Mar 30 04:00–09:00, 17:00–21:00 Mar 31 11:00–23:00
April
Apr 1 15:00–22:00 Apr 3 12:00–17:00 Apr 4 13:00–24:00 Apr 5 00:00–01:00, 17:00–24:00 Apr 6 00:00–02:00, 20:00–24:00 Apr 7 00:00–01:00 Apr 10 13:00–24:00 Apr 11 00:00–01:00, 17:00–24:00 Apr 12 11:00–19:00 Apr 14 16:00–22:00 Apr 15 07:00–21:00 Apr 16 12:00–19:00 Apr 19 21:00–22:00 Apr 20 08:00–18:00 Apr 21 13:00–21:00 Apr 22 17:00–24:00 Apr 23 00:00–01:00 Apr 24 22:00–24:00 Apr 25 00:00–01:00, 12:00–17:00, 19:00–24:00 Apr 28 19:00–20:00 Apr 29 18:00–24:00 Apr 30 00:00–02:00, 09:00–20:00
May
May 1 20:00–24:00 May 2 00:00–01:00, 20:00–23:00 May 3 13:00–17:00 May 4 05:00–12:00, 16:00–17:00 May 9 14:00–19:00 May 10 12:00–19:00 May 11 09:00–18:00 May 13 13:00–19:00 May 14 07:00–11:00, 15:00–19:00 May 15 05:00–12:00, 17:00–19:00 May 16 11:00–19:00 May 17 12:00–17:00 May 18 12:00–19:00 May 20 11:00–19:00 May 21 12:00–19:00 May 22 12:00–19:00 May 25 19:00–24:00 May 26 00:00–01:00, 13:00–19:00 May 27 13:00–22:00 May 28 12:00–19:00 May 29 15:00–19:00 May 30 12:00–22:00 May 31 14:00–20:00
June
Jun 8 13:00–18:00 Jun 9 13:00–20:00 Jun 10 13:00–20:00 Jun 12 16:00–19:00 Jun 13 16:00–21:00 Jun 14 16:00–22:00 Jun 18 12:00–20:00 Jun 20 12:00–20:00 Jun 21 12:00–19:00 Jun 24 12:00–20:00 Jun 25 12:00–20:00 Jun 27 12:00–18:00
July
Jul 5 16:00–19:00 Jul 6 12:00–19:00 Jul 8 12:00–19:00 Jul 9 15:00–21:00 Jul 10 12:00–15:00 Jul 11 14:00–19:00 Jul 12 12:00–19:00 Jul 14 15:00–19:00 Jul 15 13:00–20:00 Jul 16 12:00–18:00 Jul 18 13:00–20:00 Jul 19 14:00–19:00 Jul 21 14:00–20:00 Jul 22 16:00–20:00
August
Aug 4 13:00–19:00 Aug 5 14:00–21:00 Aug 6 12:00–19:00 Aug 7 11:00–20:00 Aug 8 12:00–20:00 Aug 9 12:00–20:00 Aug 10 15:00–18:00 Aug 12 12:00–20:00 Aug 13 12:00–18:00 Aug 14 12:00–20:00 Aug 15 13:00–21:00 Aug 16 14:00–19:00 Aug 18 14:00–19:00 Aug 19 11:00–20:00 Aug 21 13:00–16:00 Aug 25 12:00–20:00 Aug 26 12:00–19:00 Aug 28 12:00–19:00 Aug 31 12:00–19:00
September
Sep 1 12:00–19:00 Sep 3 12:00–19:00 Sep 4 12:00–22:00 Sep 6 12:00–19:00 Sep 7 15:00–19:00 Sep 8 14:00–19:00 Sep 10 12:00–19:00 Sep 12 13:00–20:00 Sep 14 06:00–12:00 Sep 16 12:00–19:00 Sep 17 15:00–21:00 Sep 18 13:00–21:00 Sep 19 13:00–20:00 Sep 20 13:00–18:00 Sep 21 12:00–19:00 Sep 22 13:00–22:00 Sep 25 13:00–20:00 Sep 26 13:00–22:00 Sep 27 12:00–19:00 Sep 28 12:00–19:00
October
Oct 8 13:00–20:00 Oct 9 12:00–21:00 Oct 10 14:00–20:00 Oct 15 12:00–20:00 Oct 16 12:00–20:00 Oct 18 12:00–20:00 Oct 19 12:00–19:00 Oct 21 12:00–19:00 Oct 22 12:00–19:00 Oct 23 11:00–18:00 Oct 25 12:00–19:00 Oct 26 14:00–19:00 Oct 27 12:00–21:00 Oct 28 12:00–19:00 Oct 30 11:00–21:00 Oct 31 11:00–22:00
November
Nov 5 11:00–19:00 Nov 7 11:00–20:00 Nov 8 11:00–20:00 Nov 9 11:00–19:00 Nov 10 11:00–21:00 Nov 12 13:00–20:00 Nov 13 12:00–21:00 Nov 14 13:00–19:00 Nov 15 13:00–19:00 Nov 16 12:00–19:00 Nov 17 12:00–19:00 Nov 21 12:00–20:00 Nov 22 12:00–19:00 Nov 23 12:00–19:00 Nov 24 13:00–20:00 Nov 25 12:00–19:00 Nov 26 12:00–18:00 Nov 27 13:00–20:00 Nov 28 13:00–20:00 Nov 29 11:00–20:00 Nov 30 13:00–18:00
December
Dec 1 12:00–21:00 Dec 2 12:00–19:00 Dec 3 12:00–21:00 Dec 5 12:00–19:00 Dec 6 12:00–19:00 Dec 7 13:00–18:00 Dec 8 12:00–20:00 Dec 9 12:00–20:00 Dec 12 13:00–21:00 Dec 13 13:00–20:00 Dec 14 13:00–19:00 Dec 15 15:00–22:00 Dec 18 12:00–19:00 Dec 19 12:00–20:00 Dec 20 12:00–19:00 Dec 22 15:00–21:00 Dec 23 11:00–19:00 Dec 24 11:00–19:00 Dec 26 11:00–19:00 Dec 28 12:00–19:00 Dec 29 14:00–22:00 Dec 30 16:00–20:00 Dec 31 11:00–17:00