Create the data set. REFLIB.CITYTEMP contains the average monthly temperatures of three cities: Raleigh, Minneapolis, and Phoenix. 
data reflib.citytemp;
   input  month faren city $;
   datalines;
   1      40.5    Raleigh
   1      12.2    Minn
   1      52.1    Phoenix
   ...more data lines...
  12      41.2    Raleigh
  12      18.6    Minn
  12      52.5    Phoenix
;