At 30…... if they were single the whole time or having smaller/more casual relationships. I would probably be alright with up to the 30 or so range.
Throw in a divorce or long term relationships or something and I would expect it to be significantly less.
The jist being I don’t like to hold peoples pasts (including sexual ones) against them. BUT, I do tend to find I’m less attracted to people who have huge numbers… But I think that just has to do with common personality traits.