I think one per year is not very much at all. I have somewhere between two and five, I think, depending on how I'm living my life right then. If I go out a lot I'll get sick more often than if I mostly stay at home. I think it makes sense - can't catch any bugs through a computer screen. Anyway, I usually manage to get sick once around the fall and at least once during winter or spring. I think I can blame it on being a weather optimist, so I'm never dressed quite warm enough :P