I'm looking for the number of traders that work for financial
institutions in three categories: financial brokerages and investment
banks; hedge funds; and mutual funds.  These traders are responsible
for buying and selling securities on behalf of their firms.  Within
this larger number of traders by category I'd like to know the
proportion that are responsible for filling orders for customers
compared to those who are trading on their firms' own accounts. 
Lastly, I'd like to know the number of traders who use quantitative
techniques for trading on their firms' own accounts.  Any information
by geography would be helpful, too.  Thanks