Order of countries on registration drop-down list

Is it possible to get one country, specifically the United Kingdom, to the top of the drop-down Country list on the registration page?  I moved it to the top of the list of countries on the 'Predefined Lists', but is still lists them alphabetically.  I also tried changing the 'value' from 'GB' to 'AAGB', but with no luck.

Any suggestions?

Thanks

If you can find the code that calls it add 'selected' to United Kingdom.
<option value="uk" selected>United Kingdom</option>