1999

7.2

2015

7.3

2014

8.5

2018

7.5

2016

7.9

2009

7.6

1980

8.2

2016

7.3

1940

7.1

1998

8.1

1994

8.7

2001

7.9

2003

7.8

2009

8.0

2017

7.3

2017

7.6

2004

7.7

1987

7.3

2012

6.4

2013

6.8