1982

6.2

2001

5.5

1986

7.6

1995

8.4

1974

7.9

1988

7.5

1992

6.9

1958

8.2

2005

7.1

1971

7.0

2004

7.2

1990

6.8

1991

8.3

1996

7.9

1991

7.5

1993

7.5

2002

6.9

2007

7.9

1994

6.1

2008

4.8