1996

6.3

1981

6.8

2008

6.7

2002

6.2

2006

6.3

2003

7.3

2000

7.0

1987

8.1

1960

7.1

2005

4.6

1955

7.0

1985

7.8

1985

6.5

1977

6.3

1951

6.9

1974

5.9

1927

7.8

1937

5.5

1968

6.1

1977

6.6