1987

7.1

1984

7.6

1991

6.4

2005

5.0

1997

6.1

1989

5.8

2.0

2007

5.0

1999

6.7

2002

5.7

1985

6.1

1986

6.9

1994

7.3

2002

7.1

1999

6.7

2003

6.7

1998

6.5

1988

7.0

2007

5.5

1999

5.0