1993

6.3

1973

5.7

1991

6.7

2002

6.2

1997

6.8

2005

6.7

2007

6.5

1975

6.3

1999

6.5

1959

6.3

1985

4.5

1986

6.3

1996

5.9

1996

6.3

2000

5.9

2000

5.8

1951

6.7

1976

6.6

2001

5.8

2006

6.5