Zero, seriously zero.. i haven't sent any in years now.. I get loads, which does make me feel a bit mean, but having made the decision years ago i cannot now seem to *undo* it.
My parents always send out a lot, though some of them are fairly minimal in what they say (to people we're closer to they'll include a more personal message). Of course they all must include our "family portrait" (which is just a photo of me and my parents) :) At least it will let some relatives know that I'm not perpetually a kid (my great aunt seems to think so).