distribute	reads
0-500	18
500-800	4
800-1000	1
1000-1200	0
1200-1400	3
1400-1600	0
1600-1800	1
1800-2000	1
2000-2200	3
2200-2400	1
2400-2600	2
2600-2800	4
2800-3000	5
>3000	143
