I think the 36-24-36 came from Hollywood. Marilynn Monroe and all
http://www.glamamor.com/2013/08/sizing-up-old-hollywood-heights-weights.html 
of coarse I have no way to make those kind of measurement on my CG character.
any one know of a way to measure your CG characters like the 36-24-36  ? in any app ?

DAZ Studio: Measure Metrics