About 27% of high school students who have used both marijuana and e-cigarettes reported using the devices to vaporize cannabis. Those most likely to vaporize pot with e-cigarettes included males and younger students.
Links:
[1] http://www.usatoday.com/story/news/2015/09/04/e-cigarettes-vape-marijuana-students-connecticut/71703472/
[2] http://rethinkpot.org/tags/vaping
[3] http://rethinkpot.org/tags/youth