distribute	reads
0-500	152641
500-800	247545
800-1000	146244
1000-1200	128607
1200-1400	114041
1400-1600	101807
1600-1800	91712
1800-2000	82975
2000-2200	76820
2200-2400	71203
2400-2600	65806
2600-2800	63299
2800-3000	62273
>3000	1641452
