distribute	reads
0-500	24832
500-800	11460
800-1000	8261
1000-1200	9328
1200-1400	12193
1400-1600	25113
1600-1800	66062
1800-2000	150767
2000-2200	259289
2200-2400	344134
2400-2600	376973
2600-2800	357560
2800-3000	303351
>3000	786471
