The "sorting" aspect of it is wrong, 2.44% is greater than 1.03% but shows up last: http://i.imgur.com/0qmIk3s.png

EDIT: I took a look at the source. There's an extra "data-" field to use as the value to sort with which is hard coded to "0" for the 2.44% row. This also answers my question of how it was sorting the textual date fields properly (each has the year in that data- field).