On the left of the list is the day number since 2000. This is why you don't see January 1, 2000. Theoretically, this list can hold more than 500 years worth of days.
Scratch 3 Patch Notes (fixed): - December days weren't showing up. - January 1, 2000 was treated as 1 day since 2000. - There was a January 32, 2000 - January had 30 days on all years except 2000.