Y Axis Text Value when using dual

[Anonymous]

Hello

I have a requirement where client want to show grade progression so the table is essentially like below

Date	Class	Grade
5/8/2012	Class2	B
1/16/2013	Class2	A+
10/17/2016	Class1	A
9/6/2017	Class1	A

I managed to use assign a numeric value to grade and dual function to create below chart

Is there a way i can get the grades listed on the y axis? currently with dual only the numeric values are showing up labels. I would like something like below unfortunately only numbers are coming up. Any other approach or solution or extension i can use to get this?

[Anonymous]

@sunny_talwar @rwunderlich