distribute	reads
0-500	3
500-800	1
800-1000	1
1000-1200	1
1200-1400	2
1400-1600	0
1600-1800	3
1800-2000	2
2000-2200	3
2200-2400	2
2400-2600	4
2600-2800	11
2800-3000	17
>3000	1845
