Table:
text: 1986 San Marino Grand Prix
Classification
Classification
Driver Constructor_ Laps Time_Retired Grid
Piercarlo Ghinzani Osella - Alfa Romeo 52 Out of Fuel 26
René Arnoux Ligier - Renault 46 Wheel 8
Philippe Streiff Tyrrell - Renault 41 Transmission 22
Teo Fabi Benetton - BMW 39 Engine 10
Jonathan Palmer Zakspeed 38 Brakes 20
Christian Danner Osella - Alfa Romeo 31 Electrical 25
Alan Jones Lola - Ford 28 Overheating 21
Andrea de Cesaris Minardi - Motori Moderni 20 Engine 23
Elio de Angelis Brabham - BMW 19 Engine 19
Jacques Laffite Ligier - Renault 14 Transmission 14
Ayrton Senna Lotus - Renault 11 Wheel Bearing 1
Nigel Mansell Williams - Honda 8 Engine 3
Johnny Dumfries Lotus - Renault 8 Wheel Bearing 17

Question: What is the average starting grid at the 1986 San Marino Grand Prix where Johnny Dumfries completed less than 8 laps?