1997

8.4

2019

8.1

2007

7.8

2000

8.2

2009

7.0

2016

7.9

2015

7.6

2011

6.9

2009

8.2

2016

8.5

2010

6.8

1997

7.9

2018

6.8

2007

7.3

2019

7.8

2014

8.5

1981

7.3

2011

8.3

2004

7.4

1987

7.3