1997

3.5

2005

6.2

1982

6.7

1984

5.6

1994

5.8

2003

6.1

1990

6.8

2002

6.4

2002

6.3

2003

6.8

2000

6.2

2004

6.6

2008

6.2

2006

6.0

2007

5.9

1981

6.4

2014

6.0

2006

5.3

2006

4.9

1969

2.8