People measure divorce rates in many different ways. For instance, you may have heard that 50% of marriages end in divorce. It's a commonly-cited statistic. However, that doesn't mean half of all marriages end every year. It just means that half will end eventually -- and even that statistic is debatable.
A better way to look at it is to see what percentage of people get divorced during a given year. You can then compare changes over time. When doing this and considering military divorce rates, studies have found that female Marines have the highest rate.