1980

8.6

2011

8.5

2016

8.6

2011

8.3

1981

8.0

1998

7.2

2005

7.7

2005

8.3

2001

8.3

2004

8.3

2004

8.6

2000

8.0

1993

6.6

2003

8.2

2005

7.8

2005

7.5

2007

8.0

2016

7.1

2015

7.4

2008

7.9