data leadyr; input primary year; 
date = mdy(1,1,year); format date monyy.; 
datalines; 
625000 1972
633000 1973
620000 1974
579000 1975
596000 1976
552000 1977
568000 1978
578000 1979
548000 1980
498000 1981
517000 1982
515000 1983
389000 1984
494000 1985
370000 1986
373000 1987
392000 1988
396000 1989
404000 1990
346000 1991
305000 1992
335000 1993
351000 1994
374000 1995
326000 1996
343000 1997
337000 1998
350000 1999
341000 2000
290000 2001
262000 2002
  ; 
proc gplot; plot primary*date; 
symbol1 v=dot c=green i=smooth60 ci=red w=2; 
run;