1997

3.0

1991

3.8

2006

5.5

1999

3.9

2005

5.6

1982

6.0

2006

6.1

1967

5.3

1988

5.6

2001

2.7

2010

5.8

1967

6.9

2009

2.9

2001

5.4

1994

4.4

2002

5.1

1965

5.2

2001

5.4

2008

3.2

1997

4.3