I have retrieve this result (pivot table) from my raw data:

---------------------+----------+
Count of student | Grade |
---------------------+----------+----------+-----------------+
Class | 1 | 2 | Grand Total |
---------------------+----------+----------+-----------------+
A | 5 | 4 | 9 |
---------------------+----------+----------+-----------------+
B | 2 | 3 | 5 |
---------------------+----------+----------+-----------------+
C | 5 | 3 | 8 |
---------------------+----------+----------+-----------------+

If I would like to create a stacked column chart with 100% for each class
but the y-axis 's value should be the as the number of students, may I know
if there is any way that i can create this? percentage is calculated using
(Grand Total / grade) , example:

for Class C, grade 1:
Percentage will be: (5/8) * 100 = 62.5%

Graph should be :
X - axis: Unit Name
Y - axis: No of users
In each line of the units should reflect the percentage of each grade for
each unit

Appreciate any advises! :)