2012

3.7

1984

6.0

2003

4.9

1987

4.8

2000

4.9

1973

3.1

1992

6.8

1995

5.7

2005

6.3

1996

5.5

1976

4.7

1987

5.3

1986

6.4

1999

7.3

1991

4.8

2004

5.7

1981

6.9

1982

6.4

2002

4.8

1997

5.2