Produce the block map. The ID statement specifies the variable that is in both the map data set and the response data set and defines map areas. The BLOCK statement specifies the variable in the response data set that contains the response values for each of the map areas. The BLOCKSIZE= option specifies the width of the blocks. The RELZERO option specifies that the block values are relative to zero.

proc gmap data=sashelp.demographics(where=(cont=95))
          map=maps.asia all;
   id id;
   block pop / blocksize=1 relzero;
run;
quit;