1982

7.6

2005

7.0

1998

7.0

1973

6.8

1989

8.3

1971

8.1

1995

7.8

2013

8.0

2008

7.6

1993

7.9

2011

7.6

2012

6.2

2001

7.8

1988

8.0

2002

8.2

1985

7.5

1994

8.0

1989

8.2

2006

8.6

2007

7.4