Bohlin, N., "A Statistical Analysis of 28,000 Accident Cases with Emphasis on Occupant Restraint Value," SAE Technical Paper 670925, 1967, doi:10.4271/670925.
The value of the three-point safety belt has been evaluated by a statistical analysis of more than 28,000 accident cases, which concerned mainly two cars only and in which 37,511 unbelted and belted front-seat occupants were involved. The safety harness concerned is the Volvo three-point combined lap and upper torso harness with a so-called slip-joint. The average injury-reducing effect of the harness proved to vary between 0 and 90%, depending on the speed at which the accident occurred or the type of injury. Unbelted occupants sustained fatal injuries throughout the whole speed scale, whereas none of the belted occupants was fatally injured at accident speeds below 60 mph. Slight injuries only, mostly single rib cracks, bruises, etc., caused by the safety belt were reported in some cases. The three-point belt proved to be fully effective against ejection out of the car. Almost all cars involved were equipped with safety belts, of which, however, only 26% on an average were used. The frequency of use increased with the age of the occupants.