1955

7.1

2001

7.4

1971

6.4

1997

7.5

1999

6.8

1985

7.7

2003

7.2

2004

7.8

2006

6.8

2006

6.7

1986

7.3

1990

6.5

2003

6.0

1986

6.7

1979

7.5

1956

7.2

2002

6.2

2008

7.2

2000

5.0

1994

6.3