As premium is the income and profit of insurance companies, they need it (and need it at the highest rate possible) to stay profitable. Therefore, in prosperous years, they will not raise the premium. In contrast, in less successful years, insurance companies tend to increase the premium rate. They need money to cover claims. To do that, they review the risk factors and reissue the premiums. Most of the action is to raise the rate. The same review can also be the result of social situations or natural disasters.