1976

7.5

1994

7.4

2005

5.2

1969

6.8

2005

6.1

2011

5.7

2003

6.5

1987

6.2

2007

5.9

2003

7.1

1983

6.8

1992

6.5

2007

5.7

1998

6.0

2002

6.9

2001

6.3

2006

5.5

2002

5.4

1985

6.1

2004

7.0