from Stanford, the number is California (38.1%) for class 2016.
http://facts.stanford.edu/undergraduate.html
The reason for the higher california residents is from school's founding charter that the school "shall serve a significant number of California residents". Still, it is very difficult to be accepted. The essays are the key after you pass the basic requirements.I am reading my daughter's essays. They are quite different from other schools.Very interesting and challenging indeed.