A: The bars for each percentage are relative to the most popular perk in that column. The most popular perk will fill its bar, and each perk under that will illustrate how popular it is relative to the most popular. So, if 22% of rolls use the most popular perk in a column and 11% of rolls use the least popular perk, the bar on the least popular perk should appear to be roughly half full. The intent of displaying it this way is to create better contrast between the options.