user: Question: How many laps led when the Grid was 15?
Columns: ['Fin. Pos', 'Car No.', 'Driver', 'Team', 'Laps', 'Time/Retired', 'Grid', 'Laps Led', 'Points']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1', '9', 'Scott Dixon', 'Target Chip Ganassi', '85', '1:47:24.2663', '6', '29', '50']
SQL:

assistant: SELECT SUM("Laps Led") FROM "Table" WHERE "Grid" = '15';