1991

6.5

2007

6.1

2003

8.3

1987

7.1

2003

7.1

2006

6.6

2001

7.5

1979

6.0

1961

4.6

1971

5.0

1982

6.0

2018

3.7

2004

4.7

2008

5.3

2013

6.7

1995

6.2

1999

5.2

1975

3.1

2006

5.2

1982

6.1