1966

6.1

1965

7.1

1977

6.8

2007

7.0

2008

5.3

1983

7.3

1995

6.1

1988

5.7

1967

5.2

1986

6.3

1971

7.2

1997

5.0

2004

5.3

2006

6.4

1996

5.4

2002

6.4

1963

6.0

1985

6.5

2001

5.8

2000

5.8