1960

6.0

2014

6.5

2010

7.2

2020

6.4

2016

6.7

2008

6.8

2006

7.6

2010

7.0

2002

6.1

2014

7.6

1985

5.4

1990

6.1

2004

6.0

1994

4.6

2015

5.7

2000

7.4

1993

7.0

2007

5.7

1973

7.1