Not sure where yahoo came up with their result, or what data it is based on. However, I downloaded every trading day of data do 2014 and took an average of the daily volume. I will double check the math tomorrow, but would encourage others to relocate the exercise with real data rather than just quoting yahoo. The basis of the scientific method is that outcomes can be verified through replication. All that to say, until I'm shown another analysis, data and all, I'm sticking with 12m average volume. Happy to be corrected, of course, but with data and analysis please.