1969

5.1

2004

7.1

2000

6.2

2004

6.3

1998

6.7

1985

4.8

1989

6.1

2002

7.7

2008

6.1

2006

6.5

2007

6.1

2006

5.6

2005

6.2

2003

5.2

1987

6.4

1996

6.1

2007

5.9

2009

6.2

1913

5.0

2004

5.7