I just did it to represent how little sugar compared to carbs there is in this brand compared to Nutella. I know a lot of people on here struggle cutting sweet things out, so this could be a potential alternative. I'm not saying it's ideal but its much better than high sugar spreads.
I worked it out by dividing the sugar content by the total carb content (including sugars) and multiplying by 100. So for the no added sugar brand...
%sugar to carbs = (7.9g (sugar) / 49.5g (total carbs)) x 100 = 15.95..... %
For Nutella...
%sugar to carbs = (54g (sugar) / 62g (total carbs)) x 100 = 87.09..... %
Probably a useless bit of information but if anything, it just shows how much unnecessary sugar is in everything