1993

7.2

2006

6.8

2020

4.3

2003

6.8

2004

7.1

2000

6.4

2007

6.8

2008

6.5

2007

5.4

2003

4.2

2007

6.3

2002

6.5

1968

5.2

1999

7.3

2008

4.0

1998

6.6

1994

8.3

2009

6.0

1999

6.8

1987

5.3