I can't find any reliable information on the net; I'm considering all monkeys in arcades blowing through their $5k deposits and professionals making millions; how many people are out there staring at NYSE level II screens every day for 6 hours while entering orders?
Since it can be done from anywhere in the world (with high speed interent connection) it's rather difficult to guestimate. Also there are 2700 stocks on NYSE. Factor in that majority of traders burn out quickly...especially in those hoop dreams. Number of trades a day per trader can be as volatile as any stock. Institutions play an important role in daily volume. But if you're taking a survey...add 1 to your tick total