1995

7.6

1997

6.6

2000

8.2

1987

6.5

1994

8.3

1983

8.2

1991

7.0

1994

6.2

2002

7.3

2006

5.8

1997

7.4

2005

6.4

1956

7.7

1999

7.4

1990

7.2

1992

6.9

1997

6.8

2005

7.1

1971

6.8

2000

6.0