The numbers are partially based on real-world traffic death rate data, which is subject to variance. It's possible that the hybrid versions of many vehicles are sold in higher numbers in inherently more dangerous places. Kind of like how many minivans outscore sedans even though minivans handle worse and are more likely to roll over. Fact is, once you get real-world data involved, the average minivan driver is much more safe and conservative than the average sedan driver, hence the reason why you see differences.