I agree with Nolo. Unless you post and tell everyone how much you make, then noone can tell. I also find this poll interesting.
I also find it interesting that people say they don't want people to know how much money they make, but they are willing to talk about their health, their love lives, the closets full of equipment, etc. I know, it's just one of those taboo subjects, as if, if you say I make a million a year, everyone is either going to hate you or ask you for money. I have a number of pretty wealthy friends, and that doesn't happen to them (including the guy who lived on the water, had a 43 foot speed boat and 2 of his 6 garage bays were populated with Dodge Vipers). This is a carryover from high school, where it's cool to be poor and disadvantaged. Although noone actually wants to be poor, they will try to act poor and bash on people with more money. It's an intersting study on social relationships.