1987

7.5

1988

6.0

2008

5.9

2000

7.2

2003

6.9

2008

6.3

1997

6.8

2013

6.1

1999

7.6

2006

6.2

1996

6.8

2012

6.4

2008

6.8

2011

7.8

1953

6.6

2015

5.5

2012

5.9

2014

7.0

2012

6.0

1943

8.2