year = 2010 
 million persons = 49.6  year = 2000 
 million persons = 47.0  year = 1990 
 million persons = 42.9  year = 1980 
 million persons = 38.1  year = 1970 
 million persons = 32.2  year = 1960 
 million persons = 25.0
The SGPlot Procedure