Is average really a good metric there or are they only including people in investment banking/trading/similar positions? Otherwise its pretty meaningless number

Is average really a good metric there or are they only including people in investment banking/trading/similar positions? Otherwise its pretty meaningless number given some of the top people make $10M+ and I don't think the back office/cleaning crew/security staff positions pay much of (if any) a premium compared to non financial firm positions.