1986

6.7

1997

8.4

2012

6.9

1975

8.4

1984

7.7

2002

7.3

1997

7.4

1977

7.7

2009

8.2

2014

7.5

2012

7.7

1992

8.1

2015

7.2

1996

8.0

1999

8.0

2011

7.5

1969

7.6

2012

6.5

2016

6.5

1998

7.4