1972

6.3

2002

6.2

2003

6.5

1996

5.7

2020

6.8

1971

7.1

1968

7.1

1993

6.9

2007

7.3

2008

6.7

2006

6.7

1972

6.5

2006

6.5

2005

5.7

1995

7.2

2002

6.3

2006

6.8

2017

7.1

2016

7.0

2010

6.4