distribute	reads
0-500	1377838
500-800	676665
800-1000	279820
1000-1200	225649
1200-1400	191688
1400-1600	169270
1600-1800	151722
1800-2000	139687
2000-2200	128698
2200-2400	120420
2400-2600	110536
2600-2800	102154
2800-3000	90557
>3000	722657
