distribute	reads
0-500	696
500-800	504
800-1000	382
1000-1200	548
1200-1400	820
1400-1600	1298
1600-1800	1871
1800-2000	2671
2000-2200	3575
2200-2400	4219
2400-2600	4593
2600-2800	4684
2800-3000	4353
>3000	16739
