Brian - I just remembered that Green's intro to my 1970 reprint of Kidson TT also gives some stats for that:
Major 66(61%), Tetratonic 1(1%), Pentachordal/tonic 3(3%), Hexachordal/tonic 17(16%), Ael 3(3%), Dor 6(6%), Mix 4(4%), Other 9(8%).
The major count is in line with Sharp's Conclusions' estimates. It's harder to say for the rest without looking more closely at the hex ones to see which sort they are.
If Sharp is right about the estimates from his complete collection, you, and others above, may be right about a bias towards non-major in the selections.