The answer is 44%. The research about Marijuana use tells us that there is approximately 15.6 percent of eighth graders account using marijuana in their times, in addition to 33.7 percent of 10th graders, and 44.4 percent of 12th graders. In the previous month, 6.5 percent of eighth graders, 16.6 percent of 10th graders and 21.2 percent of 12th graders self-confessed to marijuana use.