distribute	reads
0-500	769
500-800	876
800-1000	901
1000-1200	1657
1200-1400	3789
1400-1600	8348
1600-1800	17041
1800-2000	31468
2000-2200	49503
2200-2400	65533
2400-2600	70328
2600-2800	63526
2800-3000	53314
>3000	132688
