When converting to the US grading system, dont use percentages....a Canadian percentage point is worth way more than an American...for example, you have an 81 which is pretty damn good....equivalent to A- at UofT....however to get an A- in the States, you have to get 90%, so if you put your percentages in, you will get shortchanged....
Just do what I did....put only the letter grade in....dont worry about percentages...