distribute	reads
0-500	148349
500-800	14574
800-1000	1157
1000-1200	304
1200-1400	89
1400-1600	28
1600-1800	17
1800-2000	3
2000-2200	1
2200-2400	1
2400-2600	3
2600-2800	1
2800-3000	0
>3000	12
