1999

7.1

1995

7.1

1987

7.8

1953

5.6

2003

6.5

1978

6.2

2017

4.3

2018

5.8

2002

6.2

1997

7.0

2008

7.1

2006

6.9

2006

6.8

1989

7.6

2006

6.6

1940

6.5

1970

7.1

2009

7.0

2005

4.0

2017

5.4