distribute	reads
0-500	1
500-800	0
800-1000	1
1000-1200	0
1200-1400	0
1400-1600	0
1600-1800	2
1800-2000	1
2000-2200	4
2200-2400	2
2400-2600	11
2600-2800	14
2800-3000	31
>3000	937
