user: Question: In grid 15, how many laps were there before ending with a time of exhaust?
Columns: ['Driver', 'Constructor', 'Laps', 'Time/Retired', 'Grid']
Types: ['text', 'text', 'real', 'text', 'real']
Sample row: ['Nelson Piquet', 'Williams - Honda', 61.0, '1:39:32.583', 2.0]
SQL:

assistant: SELECT SUM("Laps") FROM "Table" WHERE "Time/Retired" = 'exhaust' AND "Grid" < 15.0;