2015

7.8

2010

7.7

2001

7.2

1998

6.8

1978

6.6

2007

6.8

2013

7.5

2005

7.1

2016

7.1

1990

8.1

1977

6.3

1997

7.6

2008

7.6

2000

6.9

1997

6.3

2015

6.9

2009

7.4

2006

7.7

2009

7.7

2016

6.7