The price of your insurance plan is based (among other things) on your age.
With each year that passes, and every year older you get, the chance of dying increases a little bit, and this is what is reflected in your price increase.
Unless you are in your early 20s, you will see your price going up by a little bit each year at your plan anniversary date. These price increases are due only to the 'age effect', never because we want to make more money out of you. The average increase is less than 5%.
We think this makes more sense than charging you a flat rate and making you 'overpay' at the beginning. Most people only keep their plan for a few years, and this way you never have to pay more than you need to.