Oh, that is so cool! Thank you for all the work you put into this!
Interesting to see the transition of top!Harry to bottom!Harry. I can imagine fanon!Draco and fanon!Harry are changing over time, but I'm not long enough in fandom to really know how Draco and Harry were seen in the beginning of fandom, compared to now.
For example, maybe there is a transition going from a snotty, feminine Draco to a more adult, redeemed Draco, or perhaps Draco is transforming into a dominant sex god. Or maybe Harry is less the Saviour and more the traumatized, troubled angsty young adult? Or maybe in earlier fics Draco was out already while Harry was questioning his sexuality, while in later fics they both were out already (and for first time sex, topping uses to be seen as less 'scary' than bottoming)?

Maybe we can also use other facts in your spreadsheet to gain some more insight? I'm thinking we could use the variable 'time frame' to see of there's a transition in time frame over time, too, and my hypothesis would be that the older they are, the more Draco's topping in fics.