2003

6.8

2005

6.5

2000

6.0

2002

4.6

2002

7.1

1994

8.3

2008

6.7

1998

6.1

2006

5.9

1990

6.1

2002

6.1

1978

6.3

1997

6.2

2002

6.6

1997

6.3

1983

6.6

1986

7.6

1996

6.2

1997

6.3

1998

6.8