That's an interesting point. At first I thought it might be incorrect because I see stations named for industry (i.e. Dow) but they appear to be operated by TransAlta.

What is def not shown is on site generation that may or may not feed the grid but does offset usage. Some of that is tracked: I know of a facility that is charged by the utility when they aren't using their on-site capacity. The utility counts it as part of the system capacity (to offset new transmission requirements). On a (very) good day, this facility generates 60% of it's own power.

There is some data out there, somewhere! It would be interesting to see what all these little bits add up to.