Year

Number of Attacks¹

Percent

Mean

Variance

Standard Deviation

Coefficient of Variation

2007

0

0.00%

2.4

5.76

2.40

1.00

2008

0

0.00%

5.76

2.40

1.00

2009

1

4.17%

1.96

1.40

0.58

2010

0

0.00%

5.76

2.40

1.00

2011

20

83.33%

309.76

17.60

7.33

2012

2

8.33%

0.16

0.40

0.17

2013

0

0.00%

5.76

2.40

1.00

2014

0

0.00%

5.76

2.40

1.00

2015

0

0.00%

5.76

2.40

1.00

2016

1

4.17%

1.96

1.40

0.58

Sum

24

Average

34.84

5.90

2.46