user: Question: How many rounds have a chassis of THL2?
Columns: ['Entrant', 'Constructor', 'Chassis', 'Engine', 'Tyres', 'Driver', 'Rounds']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Marlboro McLaren International', 'McLaren - TAG', 'MP4/2C', 'TAG TTE PO1 1.5 V6 t', 'G', 'Alain Prost', 'All']
SQL:

assistant: SELECT COUNT("Rounds") FROM "Table" WHERE "Chassis" = 'THL2';