1996

6.8

2004

7.5

2008

8.1

1999

7.9

2006

7.4

2013

7.2

2008

8.9

2000

8.0

1997

6.4

1998

7.1

2007

8.1

2008

7.7

2015

7.4

2018

7.1

2013

7.5

2001

7.8

2009

7.7

1990

6.9

2005

7.5

1988

6.8