Table:
text: 1969 South African Grand Prix
Classification
Classification
Driver Constructor_ Laps Time_Retired Grid
Jackie Stewart Matra - Ford 80 1:50:39.1 4
Graham Hill Lotus - Ford 80 + 18.8 7
Denny Hulme McLaren - Ford 80 + 31.8 3
Jo Siffert Lotus - Ford 80 + 49.2 12
Bruce McLaren McLaren - Ford 79 + 1 Lap 8
Jean-Pierre Beltoise Matra - Ford 78 + 2 Laps 11
Jackie Oliver BRM 77 + 3 Laps 14
Sam Tingle Brabham - Repco 73 + 7 Laps 17
Peter de Klerk Brabham - Repco 67 Not Classified 16
Jochen Rindt Lotus - Ford 44 Fuel Pump 2
John Surtees BRM 40 Engine 18

Question: What is the average starting grid for Jo Siffert at the 1969 South African Grand Prix?