Are you sure there is a year 0 ?!?

I fully agree [-20..10] should normally be [-20,-19,..,-1,0,1,..9,10], but start calling them "years" and things start getting muddied.

Initial solution is not set up. Neither are Example tests. Random tests missing from Submit tests. Also, I doubt this is novel content.

Please read available documentation on publishing your first kata.

Unpublishing it may save you further downvotes while you figure out what to do to make solvers happy. This isn't it.