1997

6.7

1981

8.3

1989

6.2

1985

7.2

2006

7.7

1971

7.3

1999

6.7

1993

5.9

1985

7.7

2002

8.4

2004

9.0

2001

5.0

1964

6.1

2002

10.0

2002

4.5

1985

7.0

1994

6.5

2005

8.5

1993

6.3

1979

5.6