1991

8.3

1994

8.7

2003

6.5

1984

8.4

2003

7.7

2000

6.0

1990

7.0

1999

8.5

1995

8.0

2001

6.7

1963

5.6

2012

6.0

2005

6.2

1997

6.4

1997

6.5

1999

6.8

2000

6.8

2002

6.3

1992

5.4

1982

6.3