From the FL regs:
the material has a total solar reflectance of visible light of not more than 25 percent as measured on the nonfilm side and a light transmittance of at least 28 percent in the visible light range.
Looks like 28% is the limit there. 32% here in GA for front windows....
Here is a list for all states:
http://www.tintdude.com/laws.html