Need to Sort in data table

Hi All,
I used data table in my page
http://a816-dohbesp.nyc.gov/IndicatorPublic/Secret/VisualizationData.aspx?id=18,4466a0,11,Summarize.
If I am clicking on header part of the table it is using by default sorting logic. but if data contain data+* it is not sorting in proper order. how I can  write custom logic for sorting data with * values.

Regards,
Vishal Bedre