1987

7.5

2000

7.2

2001

6.4

1988

6.0

1996

6.7

2008

7.8

2016

6.8

1990

6.3

2016

5.8

2014

6.2

2011

5.5

2004

7.1

2006

7.0

2010

6.3

1989

6.8

1953

6.8

1982

6.2

2010

6.3

2007

6.5

1996

6.8