distribute	reads
0-500	350265
500-800	246265
800-1000	104055
1000-1200	78163
1200-1400	61654
1400-1600	50105
1600-1800	41796
1800-2000	35949
2000-2200	31214
2200-2400	27316
2400-2600	23967
2600-2800	22273
2800-3000	19891
>3000	346267
