distribute	reads
0-500	17752
500-800	27360
800-1000	23536
1000-1200	26479
1200-1400	27901
1400-1600	25662
1600-1800	20390
1800-2000	14439
2000-2200	9999
2200-2400	5882
2400-2600	2870
2600-2800	1377
2800-3000	547
>3000	278
