Adding significance symbols in all panels in sgpanel

[Ksharp]

proc import datafile='C:\Users\xiakeshan\Documents\Downloads\dtr.xlsx' out=have dbms=xlsx replace;
run;



data one;
set have;
if strip(Variety)='GEM' then Variety='  GEM';
DTR=input(DTR__days_to_ripe_,best.);
run;



proc sgpanel data=one ; 
styleattrs datacolors=(red blue) datacontrastcolors=(red  blue) ;
where Season in(2021, 2022, 2023) and Harvest__month_ in(1,3,4,5,6,8) and  strip(Variety) in ('GEM','Hass');
panelby Season/rows=1 onepanel ;
vline Harvest__month_/response=DTR group=Variety grouporder=ascending markers markerattrs=(symbol=circlefilled) TRANSPARENCY=0 stat=mean ;
rowaxis values=(0 to 12 by 2) ;
run;