There are no scientific surveys that would provide any definitive answer to your question.
Some estimates from contributors:
The present estimate of people 15 to 19 in the USA is 29 million people. According to adherants.com, there are about 9% of the population who claim to be atheists (although getting good data is difficult and this may include some agnostics and non-religious people). Running this together at 9% it would seem that there would be on the order of 2.5 million atheist teens.
According to certain studies, Atheism is more popular among the younger population. In the U.S., 55 percent of atheists are under age 35, while 30 percent are 50 and over (compared to 37 percent of the total population). As a group agnostics are older than atheists, though still younger than the general population. Comparing this 2001 data with the 1990 National Survey of Religious Identification (NSRI) provides evidence of a trend towards secularization among the younger American population. See related link.
The way women are treated by these religions... I say there should be more than whatever the current percentage is.
Only 30% of teens work in the us
About 20% of teens are depressed
It is difficult to provide an exact percentage as data varies, but it is estimated that a small percentage of troubled teens in the US attend boarding schools during their high school years. Boarding schools can be an option for families seeking a structured and supportive environment for their teens who may be facing challenges.
40% of male teens cheat.
67%
90%
63% of teens can drive a stick shift.
This may not have much to do with religion but may be more socio-economic. Atheists tend to be educated and affluent relative to fundamentalist protestants who tend to be poorly educated and less affluent. Better educated and affluent people commonly delay marriage until the early to mid twenties while a high percentage of poorly educated people marry in their late teens. There is a definite correlation between teen marriage and divorce.
a lot
a lot
103.75%
the percentage of teens in group care is larger then the number of younger children 30% of teens are in group care and only 6% of young children are in group care now that is amazing