1979

6.8

2010

4.6

2014

5.9

1959

6.9

1950

7.0

1991

7.7

1986

6.4

1976

5.8

1989

7.4

1982

7.2

1990

6.9

1998

4.8

1942

3.0

2001

7.8

2004

7.3

2007

6.3

2006

5.6

1985

7.0

1996

6.5

1973

7.5