distribute	reads
0-500	735080
500-800	586187
800-1000	247930
1000-1200	178415
1200-1400	128844
1400-1600	93306
1600-1800	68604
1800-2000	50287
2000-2200	37248
2200-2400	27975
2400-2600	20568
2600-2800	15627
2800-3000	11794
>3000	39786
