Generally schools should say if they prefer in-state or out-of-state students. I've found that information on the program's website, but you can always contact the school to find out. I applied mostly to out of state programs, and I tended to apply to private schools that were out of state, unless I had above average GPA and GRE scores for the public schools. I assumed that public schools would prefer in-state students.
I wouldn't rely on the out vs in state acceptance percentages. It's likely that a majority of students will be in-state for most schools, but that doesn't mean that the school prefers in-state students. So a private school that accepted 85% in-state students last year may not actually prefer in-state students, but most of the applications may have been from in-state students.