90% of what's on the market.
You're an optimist.
What tricks do you think are just too weak to bother doing for people?
See, I've been vacillating between saying "all" or "none." If it is "all of the tricks on the market are too weak" it is because they are not developed and personalized enough. Very few can meet my standards for performance worthy. If it is "none of the tricks on the market are too weak", it is because a good performer can develop them and personalize the presentation to make them amazing.
Typically, in a book of effects, there are one or two that fit my style and that I think are strong magic. So that's around 6% if you assume 30 effects in a book.
The key here is to find what you like to perform and then find effects that fit your criteria.