I don't know the figure for Canada, but in the U.K., their National Grid, which is their gas utility, has estimated that biomethane could account for approximately, I believe, 40% of residential natural gas demand in the United Kingdom. One would expect it's a similar proportion in Canada. In terms of the dollars involved, it would take me some work to figure that out.
On February 12th, 2013. See this statement in context.