2nd screen 36830
3rd 54060
Bonus screens 3, 7, 11, 15...
After every bonus screen the doors that the keys unlock change, at screen 16 it resets
I worked out it's possible to score more than 18860 on the 1st screen. For some reason if you get a Super pill right at the start and clean-up the ghosts x4 x4 it's possible to score 20860 (with the 5k bonus)
I haven't worked out why though