I find it hard to believe that more then 40% of internet users (39% ie, 51% firefox) make more then $75k a year - that is considered a _very_ high salary outside of the US (and even in the US it isn't small change).
I would even find it hard to believe that 40% of all programmers in the world (a much more affluent demographic then all Internet users in the world) make that much.
From the comScore site: "This capability is based on a massive, global cross-section of more than 2 million consumers who have given comScore permission to confidentially capture their browsing and transaction behavior, including online and offline purchasing. "