I'm also curious to see what percentage of Merit is given to the first post of threads, and what percentage to posts inside threads.
Since I'm digging through the data anyways... - https://pastebin.com/Cf8PDFAg
This is a list of first posts in merited threads. The ones marked with "off limits" are either deleted posts or posts in "privileged" areas (e.g. Ivory Tower) that require to be logged in. Can't vouch for 100% accuracy but I spot checked a few and it looked ok. So if the "msg" field in the merit export matches one of those then it's the first post in the thread.
Based on that:
To be fair, this is heavily skewed due to people meriting theymos' merit announcement thread, satoshi's thread, HODL thread etc.