distribute	reads
0-500	267719
500-800	37563
800-1000	2375
1000-1200	708
1200-1400	211
1400-1600	106
1600-1800	44
1800-2000	31
2000-2200	28
2200-2400	28
2400-2600	16
2600-2800	16
2800-3000	16
>3000	161
