Jury Duty

I understand that Jury Duty is our civic duty and something all citizens should be at least ok with if not honored to serve. But... is it just me or does the system seem a bit unfair? Lets take my wife for example. She religiously gets called upon every year and a half to serve whereas others we know have never received a summons once in their lives. As for my personal experience, I served on a jury for five weeks a couple years ago. So, in Arizona, if you have to serve you cannot be called upon for a year and half. Shouldn't that mean that I should not be called upon for about 37 and 1/2 years? I think so, how about you?