Rick,
I think you could add this feather in it . I learned it from Reeza .

proc sgplot data=Sashelp.Class;
refline '99' / axis=x lineattrs=(color=red);
vbar Age / response=Weight transparency=0.2;
xaxis values=('11' '12' '13' '14' '99' '15' '16')
valuesdisplay=('11' '12' '13' '14' ' ' '15' '16') ;
run;