Most often in May, 24 days.
Highest follower count seen that year: 102,234.
January
Jan 1 00:00–08:00, 18:00–22:00 Jan 3 13:00–20:00 Jan 4 20:00–23:00 Jan 5 19:00–22:00 Jan 6 17:00–22:00 Jan 7 09:00–14:00 Jan 9 10:00–13:00, 16:00–19:00 Jan 10 09:00–13:00, 17:00–19:00 Jan 11 09:00–13:00, 17:00–20:00 Jan 12 09:00–12:00 Jan 13 11:00–13:00, 18:00–19:00 Jan 16 09:00–13:00, 16:00–20:00 Jan 17 10:00–14:00, 16:00–19:00 Jan 18 08:00–13:00, 16:00–20:00 Jan 19 08:00–11:00 Jan 23 13:00–19:00 Jan 24 08:00–14:00, 19:00–21:00 Jan 25 10:00–13:00, 16:00–19:00 Jan 27 12:00–14:00, 19:00–21:00 Jan 29 11:00–14:00, 19:00–21:00 Jan 31 09:00–12:00, 17:00–22:00
February
Feb 1 10:00–14:00, 17:00–21:00 Feb 2 08:00–11:00 Feb 4 13:00–14:00 Feb 5 11:00–14:00, 19:00–21:00 Feb 6 09:00–13:00, 16:00–20:00 Feb 7 09:00–11:00, 13:00–22:00 Feb 8 09:00–14:00, 17:00–20:00 Feb 19 12:00–14:00, 16:00–18:00 Feb 20 10:00–12:00, 16:00–18:00 Feb 21 09:00–14:00, 16:00–22:00 Feb 22 09:00–13:00, 16:00–20:00 Feb 23 09:00–13:00 Feb 25 15:00–16:00, 18:00–21:00 Feb 26 09:00–13:00, 15:00–20:00 Feb 27 09:00–13:00, 17:00–19:00 Feb 28 09:00–11:00, 13:00–16:00, 18:00–21:00
March
Mar 1 10:00–21:00 Mar 2 09:00–13:00 Mar 3 10:00–17:00, 19:00–20:00 Mar 5 19:00–21:00 Mar 6 09:00–13:00, 15:00–19:00 Mar 7 09:00–12:00, 14:00–21:00 Mar 8 08:00–20:00 Mar 9 09:00–14:00 Mar 10 14:00–19:00, 21:00–22:00 Mar 17 11:00–14:00, 16:00–18:00 Mar 18 09:00–13:00 Mar 21 09:00–13:00, 16:00–19:00 Mar 22 10:00–13:00, 16:00–19:00 Mar 23 11:00–13:00 Mar 26 11:00–13:00, 17:00–18:00 Mar 27 18:00–24:00 Mar 28 00:00–01:00, 12:00–15:00, 17:00–22:00 Mar 29 12:00–14:00, 16:00–23:00 Mar 30 09:00–13:00 Mar 31 16:00–22:00
April
Apr 1 15:00–24:00 Apr 2 16:00–24:00 Apr 3 00:00–03:00 Apr 4 02:00–03:00, 13:00–21:00 Apr 5 17:00–19:00 Apr 6 08:00–12:00, 15:00–17:00 Apr 7 08:00–12:00 Apr 10 10:00–19:00 Apr 11 10:00–13:00, 15:00–21:00 Apr 12 07:00–11:00, 13:00–17:00 Apr 13 08:00–10:00, 12:00–13:00 Apr 17 08:00–12:00, 15:00–20:00 Apr 18 13:00–19:00 Apr 19 08:00–19:00 Apr 20 10:00–12:00 Apr 21 10:00–13:00, 17:00–21:00 Apr 22 11:00–13:00 Apr 23 09:00–12:00, 14:00–17:00 Apr 24 10:00–11:00, 17:00–22:00 Apr 25 12:00–15:00, 17:00–18:00, 21:00–24:00 Apr 26 17:00–22:00 Apr 28 16:00–22:00 Apr 30 17:00–22:00
May
May 1 08:00–10:00, 15:00–19:00 May 2 07:00–12:00, 16:00–17:00 May 3 10:00–12:00, 14:00–17:00 May 5 14:00–16:00, 18:00–20:00 May 6 14:00–20:00 May 7 08:00–12:00, 16:00–19:00 May 8 09:00–12:00, 16:00–21:00 May 9 09:00–13:00, 17:00–21:00 May 10 14:00–20:00 May 12 17:00–20:00 May 14 14:00–21:00 May 15 10:00–13:00, 18:00–21:00 May 16 11:00–15:00, 17:00–20:00 May 17 12:00–19:00 May 19 10:00–12:00, 16:00–20:00 May 22 11:00–13:00, 17:00–21:00 May 23 12:00–18:00 May 24 11:00–13:00, 15:00–19:00 May 25 18:00–21:00 May 27 18:00–22:00 May 28 09:00–11:00, 14:00–16:00, 19:00–23:00 May 29 13:00–15:00, 20:00–23:00 May 30 13:00–23:00 May 31 15:00–23:00
June
Jun 1 20:00–23:00 Jun 2 08:00–12:00, 15:00–16:00 Jun 3 19:00–21:00 Jun 4 14:00–16:00 Jun 5 09:00–12:00, 16:00–23:00 Jun 6 09:00–14:00, 19:00–21:00 Jun 7 21:00–24:00 Jun 8 01:00–02:00, 20:00–23:00 Jun 9 15:00–17:00 Jun 11 15:00–17:00 Jun 12 10:00–11:00, 18:00–24:00 Jun 13 14:00–16:00 Jun 15 09:00–12:00, 14:00–17:00, 19:00–22:00 Jun 16 12:00–16:00, 21:00–24:00 Jun 17 17:00–24:00 Jun 18 13:00–15:00, 21:00–24:00 Jun 19 00:00–02:00, 16:00–23:00 Jun 20 00:00–02:00, 09:00–13:00, 16:00–21:00 Jun 28 21:00–22:00
July
Jul 1 18:00–24:00 Jul 2 15:00–16:00, 20:00–24:00 Jul 3 14:00–23:00 Jul 4 09:00–20:00 Jul 5 12:00–14:00, 17:00–21:00 Jul 11 08:00–15:00, 18:00–21:00 Jul 12 09:00–11:00, 13:00–15:00, 18:00–21:00 Jul 13 10:00–12:00, 17:00–23:00 Jul 15 19:00–24:00 Jul 16 15:00–16:00 Jul 17 16:00–22:00 Jul 18 19:00–24:00 Jul 19 00:00–01:00, 16:00–24:00 Jul 20 00:00–02:00, 19:00–24:00 Jul 22 21:00–24:00 Jul 24 17:00–19:00, 22:00–24:00 Jul 25 00:00–02:00, 18:00–24:00 Jul 26 18:00–23:00