OLYMPIA — Washington grew slowly — less than 1 percent — in the last year from a slight increase in people moving into the state, the Office of Financial Management said today. The annual estimate of state population said net migration, the difference between the number of people moving in and those moving out, had been falling since 2007, but that turned around in 2011 for a slight uptick. For the year ending April 1, the state gained an estimated 49,870 persons, making the overall population 6,817,770, OFM said. Seattle is the largest city, with an estimated population of 616,500. Spokane remains second, at 210.000, ahead of Tacoma at 199,600. The City of Spokane Valley remains the state’s 10th largest, with 90,550. Spokane County is the state’s fourth most populous, behind King, Pierce and Snohomish, with an estimated population of 475,600.