The number of pot smoking teens increased this year with one third of high school seniors admitting they used marijuana during the month before participating in a national survey. And it’s not just seniors. One in seven 8th graders and one in four 10th graders are also smoking pot. This data comes from the 2010 National Institute on Drug Abuse Monitoring the Future study, which has been surveying American teens since 1975. The study, designed and conducted by the University of Michigan, looked at more than 46,000 8th, 10th and 12th graders enrolled in over 350 public and private schools.