user: Question: How many years have a Surface of clay, and a Score of 4 : 0?
Columns: ['Year', 'Competition', 'Date', 'Surface', 'Location', 'Score', 'Result']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [2007.0, 'Europe/Africa Zone Group I Pool C', '18 Apr', 'clay', 'Plovdiv , Bulgaria', '3 : 0', 'Won']
SQL:

assistant: SELECT COUNT("Year") FROM "Table" WHERE "Surface" = 'clay' AND "Score" = '4 : 0';