Table:
text: 1971 Dutch Grand Prix
Classification
Classification
Driver Constructor_ Laps Time_Retired Grid
Denny Hulme McLaren - Ford 63 + 7 laps 14
Henri Pescarolo March - Ford 62 Not Classified 15
Skip Barber March - Ford 60 Not Classified 24
Peter Gethin McLaren - Ford 60 Not Classified 23
Alex Soler-Roig March - Ford 57 Engine 17
Tim Schenken Brabham - Ford 39 Suspension 19
François Cevert Tyrrell - Ford 29 Accident 12
Rolf Stommelen Surtees - Ford 19 Disqualified 18
Reine Wisell Lotus - Ford 17 Disqualified 4
Nanni Galli March - Alfa Romeo 7 Accident 20
Mario Andretti Ferrari 5 Fuel Pump 16
Dave Walker Lotus - Pratt & Whitney 5 Accident 22
Chris Amon Matra 2 Spun off 5

Question: What is the fewest laps if the driver is Rolf Stommelen and the starting grid for the 1971 Dutch Grand Prix is more than 18?

Question: What is the most laps with a field of 20 in the 1971 Dutch Grand Prix?