1991

4.7

1994

4.7

1992

6.0

2000

4.8

1997

6.7

2008

6.6

2004

5.9

1993

6.4

1994

5.7

1986

5.8

1998

7.0

2001

6.9

2002

7.5

2004

7.3

2007

7.4

1994

5.9

1983

6.1

1990

7.3

1995

6.8

1997

4.5