distribute	reads
0-500	665711
500-800	466994
800-1000	193567
1000-1200	137294
1200-1400	104235
1400-1600	81658
1600-1800	65629
1800-2000	55224
2000-2200	47520
2200-2400	41024
2400-2600	36261
2600-2800	31410
2800-3000	28247
>3000	534909
