user: Question: What is the highest year for the US Open?
Columns: ['Outcome', 'Year', 'Championship', 'Surface', 'Partner', 'Opponents', 'Score']
Types: ['text', 'real', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Winner', 1999.0, 'French Open', 'Clay', 'Venus Williams', 'Martina Hingis Anna Kournikova', '6–3, 6–7 (2–7) , 8–6']
SQL:

assistant: SELECT MAX("Year") FROM "Table" WHERE "Championship" = 'US Open';