distribute	reads
0-500	279544
500-800	273749
800-1000	434977
1000-1200	560850
1200-1400	540717
1400-1600	466862
1600-1800	390093
1800-2000	329066
2000-2200	273250
2200-2400	228205
2400-2600	192238
2600-2800	163448
2800-3000	140433
>3000	1181094
