distribute	reads
0-500	552479
500-800	717141
800-1000	297585
1000-1200	223693
1200-1400	177141
1400-1600	144512
1600-1800	119991
1800-2000	101619
2000-2200	87309
2200-2400	75562
2400-2600	65940
2600-2800	57710
2800-3000	50818
>3000	419767
