If I sort by CPA, it lists either the furthest away at top of list, or if sort by closest, all the blank CPA are listed first, and the closest CPA valued targets will be found mid list.

Is it possible to list the numerically lowest targets first in the list, of a CPA sort, so goes closest to furthest, and blank CPA last.  

The reason is so that you can see the top targets with a close CPA in a reduced size window without scrolling, which would be more effective when there are many traffic targets.