In 1915, there were 20 tax exemptions on Washington’s books. By 1935, there were nearly 80. Now, there are more than 600, roughly 450 of which would generate some revenue for the state if repealed, according to state revenue officials. (See a visual breakdown of these exemptions here.)

http://www.kplu.org/post/do-wash-state-tax-breaks-level-playing-field-or-reward-powerful