As you intuited, one of the problems is definition. It's an abiding frustration of mine that there is a standard classification of industries and, of course, it doesn't really correspond to evolving trends in industrial production. Everybody makes up their own and defines them themselves, and so we have variations on what is high tech, what is biotech, what is clean tech, and if you add them all up, particularly the ones that are promoted by the trade associations, you wind up with 500% of the Canadian economy, because people add in different things.
On April 12th, 2016. See this statement in context.