1995

6.5

1998

6.7

2005

6.3

2006

6.9

2004

6.3

1991

7.1

1984

7.1

1993

6.2

1975

8.4

1975

7.3

2006

6.6

1994

8.5

1983

4.0

2001

5.4

1986

7.9

1994

6.8

2002

6.7

1994

6.2

1988

7.5

1989

8.3