1964

7.2

1980

6.1

2014

6.2

1985

5.7

1992

7.0

1976

7.1

2008

3.7

2005

7.1

2007

6.0

2006

4.7

2010

5.6

2007

6.8

2001

7.8

2013

7.9

2005

7.1

1969

6.4

2001

6.8

1965

6.3

1993

6.6

1970

7.5