distribute	reads
0-500	1166810
500-800	522109
800-1000	120818
1000-1200	63266
1200-1400	36810
1400-1600	22643
1600-1800	15147
1800-2000	10624
2000-2200	7975
2200-2400	6044
2400-2600	4822
2600-2800	3786
2800-3000	3139
>3000	24802
