1999

6.0

2003

5.0

2001

6.7

1998

6.8

2007

5.8

2003

6.4

1988

6.5

1997

6.6

2002

6.2

2001

6.8

1978

6.3

1988

6.2

2004

6.4

1997

7.1

2006

6.2

1998

7.1

1993

6.0

1982

5.2

1988

6.6

2005

5.4