It really depends on your age, gender, address, average mileage, vehicle, history and cover.
Young drivers, inexperienced drivers are more likely to have an accident.
Males are more likely to have an accident than females
Some areas are more prone to crime.
People who drive more than 10,000 miles per year are more likely to have an accident
Some vehicles are more likely to be involved in accidents.
If you have had an accident in the past, you are more likely to have another one.
People who just have 3rd party are deemed more of a risk.
If a company have had more claims by males in a year then they will put the price up for males. Likewise, if crime goes up in an area, so does the price of insuring a vehicle in that area. This is why you need to shop around every year. Each year, one of the many companies will have been really lucky with people in your category and the price will fall for people like yourself. It is only through shopping around that you will find that company.