Well, I was sitting here cogitating in the early hours and the conclusion is- I am not a mathematical genius! tried every way I could think of How work out a formula for the increased sizes. Needs a better brain than I have.
Pattern paper was available in seven sizes: 10,12,14,16,18,20,22. = Bust Size in cms 83, 87 , 92, 97, 102. 107, 110.
Increase in from 83cms is +4 cms (4.85%), +5cms (5.7%), +5cms (5.4%), +5cms (5.15%), +5cms (4.9%), +3cms (???) Then I got lost and went to bed and had a nightmare where Stephen Hawkings appeared and called me stupid which I agreed.
Size 10 Bust 83cms appears to be the pattern paper I have i.e 1cm +small sq.
Just to confuse me further I later found on page 10 of Adapting to Fashion reference to size 8 (Bust size 80cms)pattern!
I don't know if any of this has helped or hindered you
@Addiscomber