options ls=90;

filename foo url "http://www.uvm.edu/~abh/stat295/datasets/beetles.dat";

data beetles;
     infile foo;
     input date:mmddyy10. site trap beetles;
     year = year(date);
	 drop date;
run;

proc sort data=beetles;
     by year site;
run;

data site_totals;
     set beetles;
	 by year site;
	 drop trap beetles;
	 if first.site then beetle_totals = 0;

	 beetle_totals + beetles;

	 if last.site;
run;

proc print data=site_totals;
title "Total beetles at each site";
run;

/*
	This can also be done by outputting summary statistics
	from PROC MEANS.
*/

proc means data=beetles noprint;
     by year site;
	 var beetles;
	 output out=totals_from_means(drop=_TYPE_ _FREQ_) 
                sum=beetle_totals;
run;

proc print data=totals_from_means;
title "Total beetles at each site from PROC MEANS";
run;