1968

6.9

2014

7.3

1993

5.3

2011

5.9

2010

7.4

1973

6.3

2012

5.1

2006

6.5

2010

7.1

1974

6.8

2000

5.5

2006

5.6

2015

6.1

2012

6.9

2009

6.5

1961

7.2

1977

6.8

2004

6.5

1999

6.1

1989

6.3