Table:
text: 1973 Belgian Grand Prix
Classification
Classification
Driver Constructor_ Laps Time_Retired Grid
Jackie Stewart Tyrrell - Ford 70 1:42:13.43 6
François Cevert Tyrrell - Ford 70 + 31.84 4
Emerson Fittipaldi Lotus - Ford 70 + 2:02.79 9
Andrea de Adamich Brabham - Ford 69 + 1 Lap 18
Niki Lauda BRM 69 + 1 Lap 14
Chris Amon Tecno 67 + 3 Laps 15
Denny Hulme McLaren - Ford 67 +3 Laps 2
Carlos Pace Surtees - Ford 66 +4 Laps 8
Graham Hill Shadow - Ford 65 +5 Laps 23
Clay Regazzoni BRM 63 Accident 12
Mike Beuttler March - Ford 63 Accident 20

text: 1973 Belgian Grand Prix
Classification
Classification
Driver Constructor_ Laps Time_Retired Grid
Jean-Pierre Jarier March - Ford 60 Accident 16
Jean-Pierre Beltoise BRM 56 Not classified 5
Wilson Fittipaldi Brabham - Ford 46 Engine 19
Ronnie Peterson Lotus - Ford 42 Accident 1
Peter Revson McLaren - Ford 33 Accident 10
Howden Ganley Iso Marlboro - Ford 16 Accident 21
Carlos Reutemann Brabham - Ford 14 Engine 7
George Follmer Shadow - Ford 13 Throttle 11
Jackie Oliver Shadow - Ford 11 Accident 22
Jacky Ickx Ferrari 6 Oil pump 3
Nanni Galli Iso Marlboro - Ford 6 Engine 17
Mike Hailwood Surtees - Ford 4 Accident 13

Question: What is the average starting grid with brm and under 63 laps for the 1973 Belgian Grand Prix?