distribute	reads
0-500	97303
500-800	40753
800-1000	7598
1000-1200	2528
1200-1400	903
1400-1600	326
1600-1800	148
1800-2000	76
2000-2200	36
2200-2400	16
2400-2600	10
2600-2800	7
2800-3000	5
>3000	3
