distribute	reads
0-500	10805
500-800	58005
800-1000	65051
1000-1200	63506
1200-1400	55570
1400-1600	44310
1600-1800	32426
1800-2000	22466
2000-2200	14940
2200-2400	9057
2400-2600	5295
2600-2800	2824
2800-3000	1321
>3000	854
