I'd say 0-24%. By the time they've worked their way up to star status, they probably don't enjoy it that much anymore. I've watched a couple documentaries, and in both some of the actresses stated that since they got into the porn industry, sex for them is more arousing when coupled with real love. A few said the on-camera stuff was a job, nothing more and nothing less. I don't really buy the argument that you can tell which stars are acting, and which are not. Most men can't even tell if their partner is having an orgasm, much less a pornstar whose job is to pretend they're having an orgasm.