distribute	reads
0-500	483410
500-800	160820
800-1000	61971
1000-1200	44382
1200-1400	34302
1400-1600	26866
1600-1800	22336
1800-2000	18949
2000-2200	16290
2200-2400	14186
2400-2600	12758
2600-2800	11443
2800-3000	10469
>3000	276830
