He was on the National every week if I remember right as well as being a regular on various panels. He had his own show on CBC Radio one for two decades.
So the % of editorial on CBC per week (for that brief period) would be:
(# of minutes Rex's Editorial was on TV per week / 60 * 24 * 7)
And unless someone volunteers that Global and CTV have editorial we can divide that % by 3.
By my calculation if Rex's editorial was about 3 hours per week then we are at 1% of television is editorial.
Back to the Original Post - the WALDO is correct... media is not dominated by left wing opinions...