Helps tallying grades on blackboard
Tallies grades in "Comments & Markups" section that has the format: "x/y [ grader explanation text here or empty ]" (e.g: "1/10 -9 No work shown", where x=1 and y=10 for this specific grading.)
Displays the tallied grades by modifying the "Comments & Markups" header as "Comments & Markups [sum(x)/sum(y)]"
Best practice is to define the score ratio at beginning of a comment.
For annotations that do not contain a grading, but a ratio as an explanation to a question must be observed carefully, since they would be calculated as well.
Simply download and install the extension to automatically view the sum ratio in the header.
Click on "Comments & Markups [sum(x)/sum(y)]" header or the "A+" icon on top-right of the chrome screen (as shown in the first screenshot) to view grader distribution (as shown in the second screenshot.)
Thanks to Qiuyin Ren and Syed Hossain for the idea.