1986

8.3

1999

6.8

1982

7.2

1998

7.0

2006

7.4

1989

8.3

2009

6.8

2007

7.9

2011

7.4

2009

7.9

2009

7.6

2005

7.0

1999

7.4

2010

5.0

1968

6.7

2004

7.9

2005

7.2

2002

7.2

1991

6.6

1999

7.3