1979

6.5

2006

7.3

1993

5.5

2001

7.9

1982

7.5

1984

6.6

1986

7.2

1989

5.7

1991

7.0

1994

6.5

1996

7.3

1998

6.4

2002

6.3

1948

5.6

1940

6.1

1989

2.5

1997

5.7

1925

6.7

1960

5.7

1992

5.2