The ranking is based on a ratio created by Washington Post education columnist Jay Matthews. According to the magazine, the secret recipe is:
the number of Advanced Placement, Intl. Baccalaureate and/or Cambridge tests taken by all students at a school in 2007 divided by the number of graduating seniors. All of the schools on the list have an index of at least 1.000; they are in the top 5 percent of public schools measured this way.All told, 23 schools in Washington made the complete list of 1,300 top schools. But four Washington state schools made the top 100; all four were in Bellevue. They include the International School (number 10), Newport High (31st) and Interlake (45th) and Bellevue High (62nd).
You can view the list of all 23 Washington schools here.