1974

7.0

2003

6.2

2008

6.3

1987

5.7

1972

6.9

1961

8.0

2011

7.1

2007

6.8

1959

6.1

1992

5.0

1960

7.1

1968

5.7

1997

7.4

2001

6.2

2010

6.6

2000

4.8

1998

6.2

1996

5.9

1988

6.2

1964

7.0