This PROC REPORT step produces a report on grain production. Each BY group produces a page of output, so ODS starts a new body file for each one.
proc report data=grain_production nowindows
     headline headskip;
   by year;
   column country type kilotons;
   define country  / group width=14 format=$cntry.;
   define type     / group 'Type of Grain';
   define kilotons / format=comma12.;
   footnote 'Measurements are in metric tons.';