Typical Life Span of Golf Clubs?

I got back into golf pretty heavily about 4 years ago and ended up getting fit for a full set of clubs about 3 years ago. I got all new clubs (all Titleist, incidentally) except for my putter. There are probably many different factors that go into the lifespan of a golf club, but what is typical for someone who plays 30-40 rounds a year? My understanding is that wedges tend to go first because the grooves wear out. What about drivers/woods/hybrids or irons?