1984

8.3

1990

7.8

1998

8.6

2016

8.6

1961

7.4

2007

7.6

2002

6.9

1969

6.7

1997

6.6

1994

7.6

1999

7.4

1994

8.2

2012

6.7

2015

7.0

2007

6.7

2004

7.3

2011

8.5

2014

7.2

1994

8.0

2007

8.0