The following states have certified (or all but in name) their result along with turnout 2012 and 2016
I have no idea where you are getting this information..... but according to the Oregon Secretary of State website the turnout of registered voters is actually 80.3% and not the 66.6% you have listed....
Not sure if it a typo, or if it is pulled from a bogus website, but the Oregon numbers are straight from the horse's mouth.... it also makes we wonder about the accuracy of the rest of the numbers posted about. Maybe you are posting "eligable voter" numbers instead of registered voter turnout numbers 
?
http://sos.oregon.gov/elections/Documents/statistics/participation-stats-11-2016.pdf
Registered voter (turnout) numbers are misleading.
Turnout is always based on the VEP (voting eligible population) to compare US numbers with European or other turnout.
The number of registered voters in the US is significantly lower than the VEP, therefore the turnout among RV is much higher and misleading. Many people in the US who are eligible simply are not registered to vote.
ok--- so basically what I suspected when reviewing the list....
I'm still a bit surprised at the Oregon numbers, since we have an automatic DMV registration deal for new voters and those that have to change their stuff with the DMV, however maybe it's a lag since we have something like a seven year period before people need to renew their driver's licenses.... still surprised that turnout would be higher in Colorado.... doesn't totally make sense, but I'll give you NH because of the culture of voter registration out there... 
As you can see in your link, not even OR with its new automatic DMV registration system is able to register all eligible voters.
There are still about 360.000 people who are eligible and not registered.
A good thing would be to register people to vote already when they are born in a hospital, when they pass their citizenship exams, the DMV, when they apply for federal or state aid such as unemployment services etc.
You would get very close to 100% after a while ...
