distribute	reads
0-500	1299203
500-800	542168
800-1000	195581
1000-1200	139963
1200-1400	104493
1400-1600	79172
1600-1800	61024
1800-2000	48121
2000-2200	37673
2200-2400	30078
2400-2600	24398
2600-2800	19872
2800-3000	16117
>3000	123367
