distribute	reads
0-500	362497
500-800	196784
800-1000	79609
1000-1200	57805
1200-1400	44800
1400-1600	36159
1600-1800	30469
1800-2000	26018
2000-2200	22897
2200-2400	20915
2400-2600	18855
2600-2800	17374
2800-3000	16030
>3000	440030
