1986

7.6

2004

6.8

1998

7.1

2009

6.3

1992

6.7

2002

6.0

2003

6.1

2010

7.4

1979

7.3

2015

6.4

2010

8.2

2005

6.1

1961

7.9

2016

5.7

1999

7.5

1940

7.1

2012

6.8

1961

7.7

1962

8.0

1967

6.8