distribute	reads
0-500	71599
500-800	167490
800-1000	53328
1000-1200	30032
1200-1400	18000
1400-1600	11165
1600-1800	7295
1800-2000	5015
2000-2200	3543
2200-2400	2388
2400-2600	1812
2600-2800	1268
2800-3000	924
>3000	3187
