Why decreased the percentage of study?

Question

I had 100% of the study, and became 81%.

Answer 1

Vasiliy, I think, because new courses were added "Machine learning", "Data science with Python" and "Angular + Nest JS".

Answer 2

TheWh¡teCat 🇧🇬
But which ones? I kind of went through😕

Answer 3

~ swim ~
That is, I need to become a pro user to get through them, I understand correctly?