1957

8.1

1986

6.4

1982

5.4

2006

5.0

1987

6.2

1957

7.2

1983

6.9

2002

6.1

1990

6.8

2009

6.6

2015

4.6

2003

7.0

1991

7.5

1968

7.1

1982

6.9

2012

6.5

2014

4.6

2006

6.6

2005

6.0

1966

7.2