I just did a quick search on "Alaska rape" and it seems there are a multitude of factors coming into play. Reasons given include large amounts of drunkenness, public or otherwise; greater number of men v women; isolation.
Isolation enters in in a way similar to what you saw in the movie Deliverance - clannish behavior protecting the criminal - where the perp is protected and the victim shamed and scared.
And, oh, yeah, the 20% of women raped is ESTIMATED not REPORTED. Be wary of "estimated" anything.
Snippet from a report to the State of Alaska where they flat out say it's an estimate based on SURVEY RESULTS of 11,000 women. Problems there already:
After reviewing several national sources of information about rape, we determined that the most
methodologically sound information comes from the National Women’s Study (NWS) and the
National Violence Against Women Survey (NVAWS). Data from these studies indicate that
approximately 13.4% of adult women in the United States have been victims of completed
forcible rape sometime during their lifetime. These studies also found that risk of having ever
been raped was related to a woman’s current age, her race/ethnicity, and the region of the nation
she currently lives in. Both studies also found that the majority of rapes these adult women had
experienced occurred when they were under the age of 18.
We then developed a method for estimating the prevalence of rape in Alaska using this national
information about the prevalence of rape and risk factors for having been raped. Briefly
described, we determined demographic and geographic risk factors for rape among the
approximately 11,000 women who participated in the NWS and the NVAWS. Next, we obtained
a breakdown of the Alaska population of women on these risk factors using Census data. Finally,
we used this demographic and geographic risk factor information to produce estimates of the
percentage of Alaska women who had ever been raped by statistically adjusting the
national estimate of rape based on the age and racial/ethnic breakdown of adult women in Alaska
as well as the geographic region in which Alaska is located.
Using this procedure, we estimated that approximately 20.9% of adult women in Alaska
have been victims of one or more completed forcible rapes during their lifetime. According
to the 2000 Census, there are about 210,000 women age 18 or older living in Alaska. This
means that the estimated number of adult women in Alaska who have ever been raped is
nearly 44,000. This estimate of the magnitude of Alaska's rape problem is conservative
Note they ESTIMATE the rape level in Alaska based 11,000 women who replied to a survey else where.