user: Question: How many categories of first elected are in Washington 4 district? 
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Results', 'Candidates']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Washington 1', 'Jay Inslee', 'Democratic', 1998.0, 'Re-elected', 'Jay Inslee (D) 67.7% Larry Ishmael (R) 32.3%']
SQL:

assistant: SELECT COUNT("First elected") FROM "Table" WHERE "District" = 'Washington 4';