I'd be happy to answer that question.
In terms of electricity generation, 60.2% of electricity generation is hydroelectric. Wind currently represents 1.6%, and biomass represents 1.4%. So in total, renewables represent over 63% of electricity generation.
When you add in nuclear, which is approaching 15%, it gets you to over 77% of electricity that is generated from non-emitting sources. That's where the 77% comes from.
You asked about the remainder. The remainder is mainly coal, but there is some oil-fired electricity generated in some places. For example, currently a lot of the electricity generated by the Holyrood plant in Newfoundland is oil-fired.