The (wireless substitution) beat goes on

To no one's surprise the gold standard on wireless substitution in the US, the NHIS, reports that the proportion of wireless only households keeps growing.  As of July, 2011, it was 31.6%.  That's a 1.9% increase since December of 2010 and translates into 30.2% of all US adults.  Just eyeballing the graph below it does not appear that the slope of the line that matters the most to us--the blue line--is changing much.  Hard to believe there are still people out there doing telephone research without calling cell phones.