Nobody knows how many CDs are there.
Some of the scientific approaches to find that number are a bit obscure to me.
It might help them if we bring up some creative methods to determine the number of CDs.
My suggestion
Number of high heels sold per year in size 12 and larger
divided by
Number of men with shoe size 12 (US W) and larger
equals approximately
Percentage of MTF CDs
(Assumption: On the average every CD buys one pair of heels per year, some more, some less, some don't).
What's your suggestion ?