If you add a prefix or a suffix to values in the table, they won’t be carried over to the chart. This is the default behavior of the chart engine, but you can use wpdatachart callbacks to get them to display. Every chart exposes several options that customize its look and feel. Charts usually support custom options appropriate to that visualization. You can use it for adding options that are available in Highcharts API.

In this example we will show you how to use Highcharts.setOptions to add these labels on a chart which has two Y axes.

<script type="text/javascript">
jQuery(window).on('load',function(){
    if( typeof wpDataChartsCallbacks == 'undefined' ){ wpDataChartsCallbacks = {}; }
    wpDataChartsCallbacks[94] = function(obj){
        obj.options.yAxis[0] = {
           labels: {
             format: '$ {value}'
           }
        }
        obj.options.yAxis[1] = {
           opposite: true,
           labels: {
             format: '{value} %'
           }
        }
    }
});
</script>