1980

6.6

1994

8.7

1988

7.4

2019

8.1

1994

8.3

2002

7.7

1999

7.6

2018

7.6

2007

7.3

1983

7.9

2008

8.5

2013

8.0

2009

7.6

2001

7.9

1972

8.7

1985

8.3

2006

7.8

2012

7.1

2011

6.7

2017

7.8