Today, I switched out my snow tires for summer tires. I know, I know, it's July. That's beside the point. My question is related to brakes. As usual, when I had each wheel off, I took a peek in the back of the brake caliper to see the condition of the brake pads. I know that the front pads were replaced recently (past year or so), so they looked fine. The rear pads looked good, as well. The problem is that, to the best of my knowledge, the rear pads haven't been replaced since the Summer of 2001, or about 50k miles. Is this normal for rear brake pads? I figured, given the tendency of the car to roll forward during braking, that the front pads would take up the majority of the force, but 50k miles?

I should add that the majority of driving in the period of 2001 to present was highway. Further, the past 2 years has been nearly 100% highway, due to the company Ford Exploder.