Not what you want I know, .....but I did a spreadsheet calculating the likely number of what would be reasonably expected "genuine" partakers taking into account average death rates and the reducing averages based on all available previous partaker figures I could get my hands on.
This was done several years ago when the figures had been going UP for about 3 years and I KNEW something just wasnt right!
Anyway, the expected and calculated number of partakers came out to around 1,200 for about 6 years ago and would by now be a lot lower. Personally I'd now put a conservative figure on the it at well under 1,000.
Your method is going to be woefully inaccurate as your sample data will be too small,...
I should also point out this was when I believed and felt the 144,000 was literal and must by then have been filled. As it's now turned into a "free for all" and the partakers have shot up and the Genration doctine has changed again to allow young GB annointed members then the above becomes meaningless. .... and so does the whole belief system.