distribute	reads
0-500	965
500-800	718
800-1000	417
1000-1200	442
1200-1400	501
1400-1600	641
1600-1800	850
1800-2000	1086
2000-2200	1322
2200-2400	1633
2400-2600	1928
2600-2800	2208
2800-3000	2386
>3000	32827
