1985

7.7

1996

6.4

1999

7.6

2010

3.8

1973

6.9

1994

6.7

1977

6.2

1998

7.1

2005

6.4

1987

7.3

2004

6.4

2007

6.1

1982

6.8

1986

6.7

2006

5.8

2007

5.3

2008

6.4

2006

6.2

1998

6.3

2001

5.6