For Washington, you have to go back to 1982 for Senate and 1972 for Governor. It's highly unlikely a third party candidate or independent would make it to the general election for a major race under our current top-two system, though if something like that did happen they would probably do quite well in the general. 
Hmm... I always thought that while our system does limit third party access to general elections and thus political prime time that overall the open/top-two system is more or less moot when it comes to actually effecting whether or not third party candidates get elected (obviously should a third party candidate get into the general election they would likely get at least 35-40% of the vote).
Maybe a Cascadian Independence Party should arise...
