distribute	reads
0-500	124751
500-800	6635
800-1000	556
1000-1200	151
1200-1400	45
1400-1600	20
1600-1800	18
1800-2000	13
2000-2200	14
2200-2400	14
2400-2600	10
2600-2800	6
2800-3000	4
>3000	76
