I don't think I could tell you specifically how many schools wear uniforms, however, I can tell you that there are more non-uniformed schools out there. Majority of the schools that require uniforms...
Well there is, Manatee School for the Arts (high school & middle school), Manatee Elementary, Oneco Elementary, Wakeland Elementary and that is really all I got.
This would be more or less impossible to know or find out. Whilst many countries have a blanket policy of uniforms, some schools still opt out. Some countries that have no uniform policy will have...