I don't know and that is not the point. If someone causes injury to you through negligence, it should be their responsibility to pay for the results of that negligence (through insurance or whatever).
You can't get blood from a stone and you may not be able to get anything from some drivers if they do not have the resources. This is the point about helmets. Why should I pay for medical treatment and maybe even care for life for severly injured bikers who do not wear helmets? Fault is not an issue here. If one or both parties cannot pay any judgement against them, who does? Taxpayers do. If the chances of reducing injuries that are disabling are significantly elevated, then bikers should have to show proof of financial resources for medical treatment and care or wear a helmet.