I must agree with trevorum. The numbers do sound a little dated, but yet they ring true. They are "close enough", I think. Scouting is, after all, a self selecting group, disregarding the non-participatory parent. Once a boy becomes a Cub or a Boy Scout, it will become apparent early on if they like it or not. As Scouters, we need to be sensitive to what 'enables' that self selection.
YiS SSS