nope, there are examples of posts with a percentage that have no comments. Some of the percentages appear related to upvoter count. There is one with 9 upvote

nope, there are examples of posts with a percentage that have no comments. Some of the percentages appear related to upvoter count. There is one with 9 upvoters and a percentage of 33. My guess is it's a measure of clique voting. X% of people voted on another story together. Not sure, that may be more complicated than needed, but it seems to be a percent measure of the upvoters.