Just wondering. I don't actually know.
——I wonder if they are not made available because they show a spike coincident with the introduction of The Pill in the 1960s?——
There are a lot of dollars and dogmas at stake.... Draw your own conclusions...
http://www.ratical.org/radiation/CNR/PBC/table1F.html
http://m.ije.oxfordjournals.org/content/24/2/285.abstract
http://onlinelibrary.wiley.com/doi/10.1002/ijc.2910170209/abstract