1979

6.0

2008

5.3

2004

4.8

2001

7.5

1987

7.1

2003

8.3

1994

7.4

1991

7.1

1990

6.8

1997

6.6

1992

7.4

2001

6.9

2003

7.2

2003

7.2

2006

6.6

2004

6.3

1985

5.4

2004

3.1

1999

7.1

2007

5.3