I found a nice visualisation of the most common 4-digit PIN numbers, based on 3.4 million PIN numbers from several data breaches: The 20 most common numbers make up 27% of the commonly used PIN numbers, i.e. from those 3.4 million PIN numbers used by people, more than a quarter were from this set of 20 PINs.

	PIN	Freq
#1	1234	10.713%
#2	1111	6.016%
#3	0000	1.881%
#4	1212	1.197%
#5	7777	0.745%
#6	1004	0.616%
#7	2000	0.613%
#8	4444	0.526%
#9	2222	0.516%
#10	6969	0.512%
#11	9999	0.451%
#12	3333	0.419%
#13	5555	0.395%
#14	6666	0.391%
#15	1122	0.366%
#16	1313	0.304%
#17	8888	0.303%
#18	4321	0.293%
#19	2001	0.290%
#20	1010	0.285%

A more detailed analysis is also provided, e.g. dates are also likely, either years or MMDD / DDMM (Month, Day / Day, Month).

Rule of thumb: what comes into your mind as easy to remember (e.g. birth dates) is what also comes into the mind of others -- and might therefore be tried by someone guessing your PIN code. So: do not use these!