distribute	reads
0-500	0
500-800	18
800-1000	7
1000-1200	6
1200-1400	5
1400-1600	4
1600-1800	0
1800-2000	3
2000-2200	0
2200-2400	0
2400-2600	2
2600-2800	2
2800-3000	1
>3000	2
