1991

7.1

1994

7.4

2003

8.3

1987

7.1

1999

6.8

1984

6.2

1985

7.8

1985

5.2

1992

7.4

2004

6.3

1974

7.4

1969

5.1

2006

6.5

2001

6.9

1997

6.6

2001

6.4

1970

4.2

1990

6.7

1975

5.8

1973

5.8