2007

6.4

1987

4.1

2005

7.1

2006

6.7

1959

7.9

2000

8.2

2000

7.4

2004

6.5

2000

6.0

1975

7.3

1982

7.5

2003

7.2

1985

6.6

1981

7.2

1993

6.7

1998

6.6

1992

7.4

1996

6.5

1986

6.3

1997

5.7