Factory Tint Question

I was wondering what % tint my 99 cavalier Z-24 would come with stock, the guy i bought if from said he never touched the tint on it so it would be stock. Some one has told me it is 15% tint but it dosen't look close to that. The reason im asking is i want to put 35% on the pasangers and drivers window but i dont want that tint darker the the back i would like it the same or a little lighter in the front.

Thank you for any help

Anyone know sorry i have tryed looking on the interent with no sucess and i was planning on putting on the tint friday.??