As the club treasurer I could probably come up with some data on our most recent students. But it would take a lot of time.
Best would be for students to check their logbooks. I have found students both new and add-on do complete more solo flights than needed. So that would skew your data.

I do find your initial data interesting and your cost estimate is in the "ballpark" for new pilots that I have estimated. Your cost is higher due to initiation fee and higher monthly dues then our club. We do take more 4K tows during winter training.

BillT