Here is a link to the 2002 state by state data from the NSDUH where you can find marijuana use numbers for Alaskans 12 - 17 years of age. See Table A.2:
http://www.oas.samhsa.gov/2k2State/html/appA.htm#taba.1
Note though that the study rp talks about was one performed by the University of Alaska in 1988 I believe. The numbers were then compared to SAMHSA's national numbers. SAMHSA did not do state by state numbers until 1998. The results, methodology, and so on from the University of Alaska's survey do not appear to be in print. You can't find it on the net and you can't get it through an inter-library loan. For all we know they interviewed ten long haired Eskimo teens and called it a representative sample of Alaskan teens. This was a survey conducted by college kids that was then compared to a government survey. That in and of itself should raise red flags. Who would young people be more honest with about illegal drug use, official government workers collecting data for the government, or college kids doing a survey for their school?
I doubt very seriously that teen use in Alaska was ever double the national average for teens.