1997

5.8

1991

6.1

2002

6.5

1978

6.1

2008

4.7

1980

5.7

1983

6.5

2002

5.1

1990

6.2

1985

5.7

1993

4.3

2000

5.1

2003

5.0

2008

5.5

2003

6.6

2006

4.1

1988

4.9

2003

3.9

1986

5.9

2005

4.3