1991

5.9

2002

8.4

2010

8.4

2000

6.3

2007

5.6

2012

6.6

1994

5.4

2015

4.6

1961

6.9

1981

6.5

2013

6.0

1987

6.5

1926

5.6

2009

6.6

2011

4.8

2016

6.1

2017

7.2

1998

5.2

1983

6.4

2012

7.4