SEATTLE — As voters in Washington consider whether to legalize and tax marijuana for recreational use, a new study has estimated what pot prohibition cost statewide last decade: more than $200 million. The American Civil Liberties Union of Washington released the figure today, accompanied by an interactive map showing the costs by each county. The estimates are based on data the Washington Association of Sheriffs and Police Chiefs, court filings and other agencies. They include costs from arrests, prosecution, public defense, jail and supervision. The study shows that each of Washington’s 39 counties spent at least $100,000 on marijuana enforcement from 2000 to 2010. King County spent the most — nearly $35 million. Pierce County spent more than $21 million, and Spokane County spent about $12.7 million. Initiative 502, which is on this fall’s ballot, would legalize the purchase of marijuana at state-licensed stores.