https://wiki.mozilla.org/Release_Management/Calendar

release date / central / beta / release / ESR
------------------------------------------------------------
2018-06-26  /  63  / 62 /  61  / 52.9; 60.1
2018-09-05  /  64  / 63 /  62  / 60.2
2018-10-23  /  65  / 64 /  63  / 60.3
2018-12-11  /  66  / 65 /  64  / 60.4
2019-01-29  /  67  / 66 /  65  / 60.5
2019-03-19  /  68  / 67 /  66  / 60.6
2019-05-14  /  69  / 68 /  67  / 60.7
2019-07-09  /  70  / 69 /  68  / 60.8; 68.0
2019-09-03  /  71  / 70 /  69  / 60.9; 68.1
2019-10-23  /  72  / 71 /  70  / 68.2
2019-12-10  /  73  / 72 /  71  / 68.3