40 Gen I Pokemon
35 Gen II Pokemon
34 Gen III Pokemon
27 Gen IV Pokemon
29 Gen V Pokemon
22 Gen VI Pokemon
19 Gen VII Pokemon
8 Gen VIII Pokemon

which means
35.00% of Gen II
30.56% of Gen VI
26.49% of Gen I
25.23% of Gen IV
25.19% of Gen III
21.59% of Gen VII
18.59% of Gen V
08.99% of Gen VIII

technically 3 of those Gen I Pokemon are alolan variants but I decided to count them as part of Generation I since those 3 specifically don't have their Kantonian counterparts present

>inb4 genwars