It looks like the Aerial Victories are not currently available online at AFHRA:
https://www.afhra.af.mil/Information...ctory-Credits/
There are various lists on Jan J Safarik's Aces website. The US lists are here:
http://aces.safarikovi.org/usa.warti...y.credits.html
And his AAF WWII list by name is here:
http://aces.safarikovi.org/victories...ii-by.name.pdf
It appears that list shows 15.5 victories for Whisner.
It is not clear which "version"/"Date" of the list is being displayed.