user: Question: Tell me the total number of years for wins less than 2 and class of 50cc with points of 15
Columns: ['Year', 'Class', 'Team', 'Points', 'Rank', 'Wins']
Types: ['real', 'text', 'text', 'real', 'text', 'real']
Sample row: [1969.0, '50cc', 'Tomos', 31.0, '6th', 0.0]
SQL:

assistant: SELECT SUM("Year") FROM "Table" WHERE "Wins" < 2.0 AND "Class" = '50cc' AND "Points" = 15.0;