1973

6.5

1985

7.0

1999

6.7

1985

3.1

1989

2.3

1986

6.9

1991

4.7

1994

4.7

1977

6.4

1979

5.0

1990

3.5

2005

5.6

1984

4.0

1991

6.2

1984

6.1

1985

5.4

1998

6.6

2002

5.6

1982

6.8

2001

7.0