My State Farm auto insurance policy has gone up a total of 10% for the next 6 months; 25.45% in the liability coverage alone. In the information provided, the company states: "The claim experience on your make and model (2005 Prius) of vehicle has resulted in an increase to your... coverage." Thanks, you other Prius drivers!
I still get a discount on my entire plan because of the Prius and it is extremely cheap to insure to begin with for full coverage. Well they don't call it "full coverage" anymore, but it is.
Your insurance company is scamming you. They can't raise your liability based on the actions of other drivers. Get it in writing, and report them to the appropriate government agency.