% is percentage division instead of just division so
1 % 3 results in 33
instead of
1 / 3 results in .33
The formula should always adjust the asterisks to show for the first 33% of values for each group. e.g.
if you have 9 in the group it will * the first 3
if you have 3 in the group it will * the first 1
if you have 100 in the group it will * the first 33