Tablesorter - Adding custom parser not working

Tablesorter - Adding custom parser not working

I have a colum called leverage that has values like so...
 
1:50
1:100
1:200
1:400
1:500
1:1000
 
 
Where 1:1000 is the largest and 1:50 is the smallest. However my custom parser only seems to sort them by the first number after the colon, where it should be in the ordered like above from smallest to largest.
 
Whats wrong with this code...
 
ts.addParser({
        id: "leverage",
        is: function (s) {
            return /\:$/.test($.trim(s));
        }, format: function (s) {
            return $.tablesorter.formatFloat(s.replace(new RegExp(/:/g), ""));
        }, type: "numeric"
    });