Related: this
So I have just run a query at SEDE, and get the following data:
- Upvotes cast by rep 101 users: 66626
- Upvotes cast by all users: 1777003
Hence by simple calculation, we get $$\frac {66626} {1777003} * 100\% = 3.7493\%$$ Which is quite a lot.
Note: ironically, I am also a 101 user, and has cast 5 upvotes (and posted 1 answer, in which I messed up) but I promise that I have at least some ideas about what I am voting on.
SELECT SUM(UpVotes) as upvotes FROM Users WHERE Reputation = 101
... I think this is exactly 101 rep users. $\endgroup$