distribute	reads
0-500	127951
500-800	95532
800-1000	57604
1000-1200	52638
1200-1400	47932
1400-1600	43509
1600-1800	38683
1800-2000	35420
2000-2200	32101
2200-2400	29333
2400-2600	27340
2600-2800	24926
2800-3000	22069
>3000	260468
