distribute	reads
0-500	0
500-800	176
800-1000	33
1000-1200	20
1200-1400	9
1400-1600	7
1600-1800	2
1800-2000	3
2000-2200	0
2200-2400	2
2400-2600	0
2600-2800	2
2800-3000	0
>3000	7
