2 2 2 3 1 4 1 6 1 7 1 8 1 9 1 11 1 12 1 13 1 16 3 17 1 19 3 21 1 22 2 23 1 24 1 28 1 29 2 30 1 31 1 33 1 34 1 35 1 36 1 40 1 42 1 43 1 45 1 49 1 55 1 63 1 67 2 72 1 140 2 171 1 303 1 347 incidence Frequency Mean = Std. Dev. = N = Histogram