1966

8.5

2013

7.2

2006

6.2

1975

6.4

2018

6.6

2004

6.5

2002

6.3

2010

7.8

1999

6.7

1971

5.9

2012

6.4

1993

5.6

2008

6.8

1994

6.3

1990

6.1

2011

6.2

2002

6.2

2001

6.7

1972

6.2

1997

6.2