Hello David.

This can't be inherited from the table's prefix or suffix, so you will need to use wpDataCharts callbacks to display the percentage.

Take a look at this page, where we explained how this can be added on a chart with two Y axes. The same logic applies to one axis.

• Every chart exposes several options that customize its look and feel. Charts usually support custom options appropriate to that visualization. wpDataChart callbacks allow adding options that are available in Google Charts API, Highcharts API, and Chart.js API. 

• All necessary resources are available in charts engines API (depends on which one you use). Every engine has a different approach to chart settings. In wpDataChart callbacks, you have to adopt those settings to the wpDataChart object (you can take a look at examples for each engine in our documentation, and also in the Support help center). A huge number of examples for any area of programming can be found on stackoverflow.com (typing your problem in google and at the end add "site: stackoverflow.com" and Google will search only that website). Also, a lot of examples of charts, chart settings, and customization can be found on jsffidle.net (typing in google for example "line chart highcharts jsffidle")
• Please note that using hooks or wpDataTable and wpDataChart callbacks requires a certain level of programming skills and included support refers only to advice.

Hi again David.

Can you try using this callback?

<script type="text/javascript">
jQuery(window).on('load',function(){
    if( typeof wpDataChartsCallbacks == 'undefined' ){ wpDataChartsCallbacks = {}; }
    wpDataChartsCallbacks[7] = function(obj){
        obj.options.yAxis[0] = {
           labels: {
             format: '{value}%'
           }
        }
    }
});
</script>

If that doesn't work, please provide me a temporary WP-admin (administrator) user for your site where this happens, so we could log in and take a look ‘from the inside’ as that’s the most efficient way to see and resolve the issue. 

We do not interfere with any data or anything else except for the plugin (in case that’s a production version of the site), and of course, we do not provide login data to third parties. 

You can write credentials here just check PRIVATE Reply so nobody can see them except us.

I can't promise anything, but I can take a look. Make sure to tell me what the chart ID is, and on which page it is located, so I know where to look.