1991

5.9

1999

6.2

1974

4.0

2002

7.4

1985

7.3

1952

6.7

1998

5.5

2004

6.6

2005

7.2

1989

7.5

1996

7.0

2006

5.0

1996

6.9

2002

7.1

1999

7.0

1996

7.5

2001

6.0

2007

7.6

1995

7.0

1998

7.3