1974

8.6

2006

8.0

1990

7.5

2010

5.7

1987

7.8

1979

7.3

2000

7.7

1987

8.1

1998

6.6

2009

7.2

2008

6.3

2013

7.3

1987

7.3

1959

8.0

1989

5.2

2010

7.4

2010

8.4

2007

5.8

2008

6.7

2004

7.3