distribute	reads
0-500	20041
500-800	14805
800-1000	9364
1000-1200	8588
1200-1400	8087
1400-1600	7804
1600-1800	6782
1800-2000	6484
2000-2200	5961
2200-2400	5653
2400-2600	5316
2600-2800	5338
2800-3000	4403
>3000	77308
