@sain,
Please check this documentation page for an example on using the yValueFormatString
property and the different formatting options supported. Also, please take a look at this gallery page example of a pie chart with percentage values in the tooltip as well as indexlabel.
In your case you can set yValueFormatString: "{y}%"
if you want to show the value in percentage or yValueFormatString: "{y}'%'"
if you want to add % symbol along with the current y-value.
—
Thangaraj Raman
Team CanvasJS