The ability and potential as stated on this site.

Hello all,

I was wondering what the meaning was of the percentage of ability and potential, I know for what the random potential of -6,-65, -7.. etc stands. However, when looking up a player on this website you will not always find these 'negatives', but also a percentage of 70,80% ability and 73,20% potential, but how to place this figure... is it like -7 till -75? So, a range from 110-150?

Also, you will see with CR7, for instance, for consecutive fm 14 till 18 a potential of 81, 86, 91, 89, 89 respectively(in percentage).
For CA it's exact the same amount every year, something is off here... or I just missed the meaning of these figures.

I wish I can read the potential on this site, it's so annoying without answers