Nah I think the more interesting metric would be total sales to populations served by both CVS and one or both of TJ and WF. There may be many more CVSes, but,

Nah I think the more interesting metric would be total sales to populations served by both CVS and one or both of TJ and WF. There may be many more CVSes, but, owing to their small size, there are also many more CVSes serving a given population than there are WFs and TJs, such that those populations have the ability to choose one or the other.