1999

7.4

2015

7.2

2014

7.9

2012

7.9

2009

7.6

1962

7.8

2016

7.3

2005

7.8

2014

6.3

1968

7.1

2004

7.9

1971

7.8

2011

6.4

2003

7.8

1989

7.7

1975

6.9

2000

7.0

1990

7.6

2013

6.8

2017

7.5