Seattle's growth is tied to
new housing construction. We were adding 10,000 units per year at the peak. (ps the link is about "finaled" permits, ie completed projects)
Further, the 2010 base was a time of high vacancies due to a building boom and economic drop. Just filling those units represented significant growth. Also, the rise in prices has resulted in more roommates.
Do we end with 760,000, i.e. growth of 152,000? I don't know. But it would make sense.