Here we go.
Clear annealed, passing 89% of UV light (so blocking 11%).
Automotive tempered glass (2005 Ford Focus, my new car), passing 40% of UV light:
Automotive tempered + Geoshield 50% ceramic tint, passing 0% of UV light:
This meter is actually for eye glasses. As you can see the scale is 1 - 3% transmission as "safe"