It would be nice to see a separate column in stats but it's not like they are hiding it from you for some devious reason as you seem to imply.
Use their sub tracking feature. That's what it's there for.
Assuming you don't have a million hardcoded links, if you want to check on rebills change your link once a month.
eg ....p123456.submarch2005, p123456.subapril2005 etc
or if you want to test how something you tweaked is working
use p123456.submysupercoolnewpage
etc
