In general, the rental market goes with median income. People don't borrow money to pay the rent (or not for very long), they pay out of current income. Supply is also a factor, but by they speed at which they've been throwing up houses, condos, townhouses as well as rental properties, there are plenty of places to live.
Here's someone else's opinion:
http://www.seattlecondoreview.com/2007/11/so-right-now-we.html
An increase in rent from 935 to 1160 over 6.5 years only represents a 2.7%/year increase. Which is pretty much in line with inflation.