Frequencies for first 10,000 rows of rail variable in accident dataset : Rail Grade | Xing ID | Freq. Percent Cum. ------------+----------------------------------- 0000000 | 9,917 99.17 99.17 003639R | 1 0.01 99.18 025132G | 1 0.01 99.19 026314W | 1 0.01 99.20 026647X | 1 0.01 99.21 027636N | 1 0.01 99.22 028822T | 1 0.01 99.23 028924L | 2 0.02 99.25 028925T | 1 0.01 99.26 125384R | 1 0.01 99.27 244848N | 1 0.01 99.28 247238R | 1 0.01 99.29 425345W | 1 0.01 99.30 425358X | 1 0.01 99.31 425570N | 1 0.01 99.32 426394W | 1 0.01 99.33 431270N | 1 0.01 99.34 434200J | 1 0.01 99.35 434203E | 1 0.01 99.36 434300N | 1 0.01 99.37 434301V | 1 0.01 99.38 438576S | 1 0.01 99.39 503987A | 1 0.01 99.40 504091C | 1 0.01 99.41 597684A | 1 0.01 99.42 621325Y | 1 0.01 99.43 622080N | 1 0.01 99.44 625085H | 1 0.01 99.45 626869N | 1 0.01 99.46 636528X | 1 0.01 99.47 636532M | 1 0.01 99.48 637853X | 1 0.01 99.49 664060T | 1 0.01 99.50 671740F | 1 0.01 99.51 672547X | 1 0.01 99.52 672553B | 1 0.01 99.53 713665R | 1 0.01 99.54 726378R | 1 0.01 99.55 726765H | 1 0.01 99.56 731870U | 1 0.01 99.57 741722C | 1 0.01 99.58 741795M | 1 0.01 99.59 742104F | 1 0.01 99.60 746010T | 1 0.01 99.61 746927M | 1 0.01 99.62 747282J | 1 0.01 99.63 747953F | 1 0.01 99.64 752064M | 1 0.01 99.65 752760S | 1 0.01 99.66 755013M | 1 0.01 99.67 755034F | 1 0.01 99.68 756749F | 1 0.01 99.69 761424G | 1 0.01 99.70 761529V | 1 0.01 99.71 787791P | 1 0.01 99.72 804336U | 1 0.01 99.73 810871U | 1 0.01 99.74 810881A | 1 0.01 99.75 810899K | 1 0.01 99.76 810979D | 1 0.01 99.77 811040M | 1 0.01 99.78 811061F | 1 0.01 99.79 833848P | 1 0.01 99.80 834216K | 1 0.01 99.81 856721R | 1 0.01 99.82 865192J | 1 0.01 99.83 865326F | 1 0.01 99.84 868345V | 1 0.01 99.85 9999999 | 15 0.15 100.00 ------------+----------------------------------- Total | 10,000 100.00 by Jean Roth , jroth@nber.org , 18 Apr 2016