1988

7.3

2005

6.6

1999

6.6

2002

6.5

2003

6.5

1998

7.1

1981

6.8

1997

5.2

1999

6.1

1992

7.8

1999

6.8

2005

4.4

2001

6.7

2000

6.7

1995

7.3

1996

6.8

1996

6.2

1993

7.2

1995

6.9

2002

6.0