distribute	reads
0-500	4
500-800	7
800-1000	2
1000-1200	1
1200-1400	2
1400-1600	3
1600-1800	3
1800-2000	3
2000-2200	0
2200-2400	4
2400-2600	5
2600-2800	3
2800-3000	3
>3000	12
