The chart represents the the glycemic load per serving:
To understand a food's complete effect on blood sugar, you need
to know both how quickly the food makes glucose enter the bloodstream, and
how much glucose it will deliver. A separate value called glycemic load does
that. It gives a more accurate picture of a food's real-life impact on
The glycemic load is determined by multiplying the grams of
a carbohydrate in a serving by the glycemic index, then dividing by 100.
A glycemic load of 10 or below is considered low; 20 or above is considered
high. Watermelon, for example, has a high glycemic index (80).
But a serving of watermelon has so little carbohydrate (6 grams) that
its glycemic load is only 5.1
The data can be found in the Harvard
Health Publications article Glycemic index and glycemic load for 100+ foods:
Measuring carbohydrate effects can help glucose management