Well, with the combined factors of WWII keeping the men busy, and the general conception around that time that "computing" was boring data-entry work -- and so, fit for women -- the fact that those handful of pioneering women (Hopper et al) were alive around early/mid 20th century isn't coincidence. The last real "wave" of women programmers has long been over..
@poorelise - I admit that I'm ignorant of modern figures in programming who are women. What I meant with "wave" is that the famous women programmers that are often mentioned/taught about, cluster around a time period where we can identify a trend.
