Year

S ± 0.6

D

C

2008

3.1

6

0.59

2009

3.0

7

0.59

2010

3.0

7

0.61

2011

3.0

6

0.62

2012

2.9

7

0.65

2013

3.0

6

0.63

2014

3.0

6

0.63

2015

3.0

6

0.65

2016

2.9

7

0.68

2017

2.9

7

0.68