1993

6.3

1997

6.8

1966

7.1

2003

6.9

1990

6.2

1991

6.7

1984

6.0

1998

6.9

2002

6.2

1997

6.8

2003

6.8

1987

6.4

2005

6.7

2007

6.2

2006

6.6

2005

7.0

2003

7.2

2006

7.1

1992

6.8

1991

7.6