distribute	reads
0-500	3995
500-800	3397
800-1000	2853
1000-1200	3778
1200-1400	4882
1400-1600	6947
1600-1800	10013
1800-2000	13369
2000-2200	17413
2200-2400	21728
2400-2600	25385
2600-2800	26975
2800-3000	27661
>3000	116900
