The University of Toronto recently published an interview with Professor Chris Cavacuiti of the department of family and community medicine at St. Michael’s Hospital in which he quotes a study that found bicyclists are the cause of less than 10% of bike-car accidents. From the interview:
While there is a public perception that cyclists are usually the cause of accidents between cars and bikes, an analysis of Toronto police collision reports shows otherwise: The most common type of crash in this study involved a motorist entering an intersection and either failing to stop properly or proceeding before it was safe to do so. The second most common crash type involved a motorist overtaking unsafely. The third involved a motorist opening a door onto an oncoming cyclist. The study concluded that cyclists are the cause of less than 10 per cent of bike-car accidents in this study.
The available evidence suggests that collisions have far more to do with aggressive driving than aggressive cycling.
I believe the study quoted by Professor Cavacuiti is the Toronto Bicycle/Motor-Vehicle Collision Study (2003). The full study can be viewed at the link below.