Most often in December, 31 days.
Highest follower count seen that year: 18,260.
July
Jul 25 02:00–03:00, 15:00–16:00 Jul 26 02:00–03:00 Jul 28 08:00–09:00 Jul 29 17:00–18:00 Jul 30 02:00–03:00
August
Aug 1 03:00–04:00 Aug 7 02:00–03:00 Aug 8 02:00–03:00 Aug 10 01:00–02:00 Aug 11 03:00–04:00 Aug 12 03:00–04:00 Aug 14 02:00–03:00, 13:00–14:00 Aug 15 01:00–02:00 Aug 16 10:00–11:00, 17:00–18:00 Aug 18 01:00–02:00, 12:00–13:00, 16:00–17:00 Aug 19 01:00–02:00 Aug 20 01:00–02:00, 13:00–14:00, 20:00–21:00 Aug 21 17:00–18:00 Aug 22 01:00–04:00, 17:00–20:00, 22:00–23:00 Aug 23 13:00–14:00, 19:00–21:00, 23:00–24:00 Aug 24 18:00–20:00 Aug 25 01:00–05:00, 14:00–15:00, 17:00–18:00, 20:00–21:00 Aug 26 01:00–02:00, 12:00–13:00, 18:00–20:00, 23:00–24:00 Aug 27 12:00–13:00, 15:00–19:00 Aug 28 00:00–02:00, 13:00–14:00, 19:00–20:00 Aug 29 00:00–01:00, 16:00–17:00 Aug 30 02:00–03:00, 12:00–13:00, 23:00–24:00 Aug 31 02:00–03:00, 23:00–24:00
September
Sep 1 01:00–02:00, 14:00–16:00, 19:00–20:00 Sep 2 01:00–02:00, 16:00–17:00 Sep 3 01:00–02:00, 16:00–17:00, 22:00–23:00 Sep 4 01:00–02:00, 12:00–13:00, 19:00–20:00 Sep 5 01:00–02:00, 11:00–12:00 Sep 6 01:00–02:00, 17:00–19:00 Sep 7 03:00–04:00, 18:00–19:00, 22:00–23:00 Sep 8 02:00–03:00, 14:00–16:00 Sep 9 01:00–02:00, 14:00–15:00 Sep 10 02:00–03:00, 05:00–06:00, 12:00–13:00, 17:00–18:00 Sep 11 01:00–02:00, 06:00–07:00, 17:00–18:00 Sep 12 01:00–02:00 Sep 13 20:00–21:00 Sep 14 21:00–22:00 Sep 15 01:00–02:00, 12:00–13:00, 16:00–17:00 Sep 16 01:00–02:00, 04:00–05:00, 14:00–15:00, 19:00–20:00, 23:00–24:00 Sep 17 01:00–02:00, 14:00–15:00, 18:00–19:00 Sep 18 02:00–03:00, 14:00–17:00, 22:00–23:00 Sep 19 01:00–02:00, 14:00–15:00, 23:00–24:00 Sep 20 14:00–15:00, 19:00–20:00 Sep 21 01:00–02:00, 14:00–15:00 Sep 22 01:00–02:00, 22:00–23:00 Sep 23 02:00–03:00, 15:00–19:00 Sep 24 02:00–03:00, 07:00–08:00, 13:00–20:00 Sep 25 01:00–02:00, 15:00–21:00, 23:00–24:00 Sep 26 02:00–03:00, 16:00–21:00 Sep 27 02:00–03:00, 14:00–15:00, 17:00–21:00 Sep 28 00:00–01:00, 04:00–05:00, 13:00–15:00, 18:00–21:00 Sep 29 01:00–03:00, 12:00–15:00, 18:00–19:00, 21:00–23:00 Sep 30 02:00–03:00, 14:00–15:00, 17:00–19:00, 21:00–22:00
October
Oct 1 01:00–02:00, 07:00–08:00, 12:00–14:00, 16:00–19:00 Oct 2 12:00–18:00 Oct 3 03:00–05:00, 12:00–13:00, 15:00–16:00, 19:00–21:00 Oct 4 03:00–04:00, 14:00–15:00, 22:00–23:00 Oct 5 03:00–04:00, 15:00–16:00, 18:00–19:00 Oct 6 03:00–04:00, 15:00–18:00, 21:00–22:00 Oct 7 00:00–03:00, 12:00–16:00, 18:00–19:00 Oct 8 01:00–02:00, 14:00–15:00, 19:00–24:00 Oct 9 02:00–03:00, 16:00–17:00, 19:00–20:00, 23:00–24:00 Oct 10 00:00–01:00, 15:00–16:00 Oct 11 00:00–01:00, 13:00–14:00, 20:00–21:00 Oct 12 02:00–03:00 Oct 13 01:00–02:00, 04:00–05:00, 18:00–19:00, 22:00–23:00 Oct 14 14:00–15:00, 18:00–19:00 Oct 15 15:00–16:00, 18:00–19:00, 22:00–23:00 Oct 16 01:00–02:00, 17:00–18:00 Oct 17 00:00–01:00, 17:00–18:00, 23:00–24:00 Oct 19 02:00–03:00 Oct 21 01:00–02:00, 18:00–19:00 Oct 22 16:00–17:00, 20:00–21:00 Oct 23 02:00–03:00 Oct 26 02:00–03:00 Oct 28 18:00–19:00 Oct 31 07:00–08:00
November
Nov 1 04:00–05:00 Nov 3 13:00–14:00 Nov 4 17:00–18:00 Nov 5 16:00–17:00 Nov 10 15:00–16:00 Nov 13 03:00–04:00 Nov 14 03:00–04:00 Nov 15 02:00–03:00, 14:00–15:00, 17:00–18:00 Nov 17 13:00–14:00 Nov 18 02:00–03:00 Nov 19 03:00–04:00 Nov 20 15:00–16:00 Nov 21 03:00–04:00, 14:00–15:00 Nov 23 05:00–06:00 Nov 25 14:00–15:00 Nov 26 19:00–20:00 Nov 27 14:00–15:00, 20:00–21:00 Nov 28 01:00–02:00, 14:00–15:00, 18:00–19:00, 21:00–22:00 Nov 29 19:00–20:00, 22:00–23:00 Nov 30 03:00–04:00
December
Dec 1 03:00–04:00, 13:00–14:00, 17:00–18:00, 23:00–24:00 Dec 2 01:00–03:00, 14:00–19:00, 21:00–22:00 Dec 3 03:00–04:00, 13:00–14:00, 16:00–17:00, 19:00–21:00 Dec 4 02:00–03:00, 16:00–19:00, 21:00–22:00 Dec 5 01:00–02:00, 17:00–18:00, 21:00–23:00 Dec 6 01:00–02:00, 18:00–19:00 Dec 7 03:00–04:00, 14:00–15:00, 17:00–19:00 Dec 8 01:00–02:00, 14:00–15:00, 17:00–18:00, 20:00–21:00 Dec 9 01:00–02:00, 17:00–18:00, 20:00–23:00 Dec 10 03:00–04:00, 13:00–14:00, 16:00–19:00, 23:00–24:00 Dec 11 04:00–05:00, 12:00–13:00, 15:00–16:00, 19:00–20:00 Dec 12 00:00–01:00, 05:00–06:00, 16:00–17:00, 22:00–23:00 Dec 13 04:00–05:00, 15:00–16:00 Dec 14 04:00–05:00, 17:00–20:00 Dec 15 05:00–06:00, 15:00–22:00 Dec 16 03:00–04:00, 18:00–19:00 Dec 17 03:00–04:00, 13:00–14:00, 16:00–19:00 Dec 18 03:00–04:00, 13:00–14:00, 16:00–17:00 Dec 19 04:00–05:00, 14:00–15:00, 18:00–19:00, 23:00–24:00 Dec 20 02:00–03:00 Dec 21 02:00–04:00, 16:00–17:00, 22:00–23:00 Dec 22 03:00–04:00, 18:00–19:00 Dec 23 03:00–04:00, 13:00–14:00, 22:00–23:00 Dec 24 04:00–05:00, 20:00–21:00 Dec 25 17:00–18:00, 23:00–24:00 Dec 26 04:00–05:00, 14:00–15:00, 18:00–20:00 Dec 27 05:00–06:00, 19:00–20:00 Dec 28 03:00–04:00 Dec 29 02:00–03:00, 14:00–15:00, 20:00–21:00 Dec 30 04:00–05:00, 14:00–15:00, 17:00–22:00 Dec 31 04:00–05:00, 18:00–19:00