1981

7.8

1985

7.7

1993

7.1

1997

7.4

2017

7.6

2014

8.3

2016

6.9

2019

6.6

2015

7.8

2010

6.7

1985

7.9

1987

7.0

2011

7.0

2017

7.7

2019

7.6

2019

6.6

2007

6.7

2014

7.0

2004

7.2