1998

7.7

2008

8.5

2014

8.0

1968

8.1

1994

8.5

1978

7.4

1962

7.0

2012

7.4

2017

7.6

1994

8.7

1997

7.9

2007

7.5

1999

8.2

1989

8.3

1982

7.5

1972

8.7

2013

8.1

2011

6.2

2006

7.9

1998

8.2