(Said in a Seinfeld voice) What's the deal with 1969 high numbers??

[JTysver]

I started looking up birth rates and set sizes and thought that there should be some correlation to the distribution. However, I pretty much realized that Topps probably was doing some marketing in a sense, but were not basing distribution upon the number of births etc. I think it is as simple as Topps probably released 1961 high numbers too late and realized that mistake and fixed it the following year.
We have to remember, Topps was the only game in town and they were feeling their way through the business end of things back then.

Topps probably was constantly playing with the dates and distribution to see what worked best and stretched the dates back in 1966 after having sold them too early in 1965. My guess is that their September sales or even August sales numbers dropped off a bit in 1965 because kids already bought what they wanted. After feeling their way through it, they probably decided to make an earlier distribution date again for the later series in 1968.