How to not print the indicator variable in PROC SGPANEL?

[NonSleeper]

This is an example of PROC SGPANEL:

proc sgpanel data=sashelp.prdsale;
where product in ("CHAIR" "SOFA");
title "Yearly Sales by Product";
panelby year/spacing=5 novarname rows=2 columns=1;
vline month/response=actual group=product markers;
run;

The output graph prints year (1993, 1994) as indicator for each panel. How can I not print it (and where will the option be put in the program)?

I'm asking this in cases where the purpose of dividing data into panel is because there will be too many lines to pack in a graph, i.e., the variable used for such division has no actual meaning.

 

[DanH_sas]

What version of SAS are you using? Starting with SAS 9.4, you can use the NOHEADER option on the PANELBY statement to do what you want.