Date sorting on MM/dd/yy format problem

When sorting on a column with dates in both 20th and 21st century, the 20th century dates appear first when sorting descending order. The simple solution would be to change my format to MM/dd/yyyy, but that is not an option because the rest of the site uses MM/dd/yy and I want to keep it consistent.

ie

desc
11/11/99
11/11/98
11/11/04
11/11/01

Any thoughts?