1971

5.3

1983

5.1

1996

6.7

2017

4.1

1976

4.2

2004

5.6

1987

7.3

2009

4.5

1999

6.8

1993

5.5

2001

6.2

2006

5.4

2004

4.8

2001

6.1

2005

5.9

2001

7.3

1984

5.9

1997

6.8

2005

6.7

2005

6.8