How many people have taken Andrew Ng&#x27;s machine learning online class? That is just one source. How many people support ML with low level mechanical Turk type work annotating data for ML? But yes, my figure might be high right now, but ML is a fast growing field. BTW, I remember in the 1980s how international conferences would attract just small crowds, although we made up for small numbers with lots of hype and enthusiasm. And there would not be very many conferences compared to today.