Year

Number of Attacks¹

Percent

Mean

Variance

Standard Deviation

Coefficient of Variation

2007

43

12.32%

34.9

65.61

8.10

0.23

2008

48

13.75%

171.61

13.10

0.38

2009

35

10.03%

0.01

0.10

0.00

2010

19

5.44%

252.81

15.90

0.46

2011

38

10.89%

9.61

3.10

0.09

2012

46

13.18%

123.21

11.10

0.32

2013

39

11.17%

16.81

4.10

0.12

2014

24

6.88%

118.81

10.90

0.31

2015

16

4.58%

357.21

18.90

0.54

2016

41

11.75%

37.21

6.10

0.17

Sum

349

Average

115.29

10.74

0.31