I suspect that there are more than a few conservative actors and such, but they are not secure enough in their star status to make their position public.
About 30%, and yes, they lay low.
There are conservatives in Hollywood, but aside from the blockbuster stars, the rest of them stay in the closet, for fear of being blacklisted. More of them are starting to come out of the closet, but what I'll describe in moment is the reason many of them keep their views to themselves.
A few years ago, the ridiculously vapid "People" magazine ran a little snippet on Sharon Laurence mentioning she was a Republican. She got angry calls from directors, producers, and other fellow useful idiots(she's really a liberal) for weeks, until she corrected the mistake.
Only the big stars like Ahnold, Mel Gibson, and Bruce Willis can openly state their conservative views and get away with it. Hollywood loves to castigate itself for the blacklist of commies in the 50's, but has no hesitance to do it all over again today for people who dare be Republican.