distribute	reads
0-500	177
500-800	65
800-1000	1
1000-1200	2
1200-1400	3
1400-1600	2
1600-1800	1
1800-2000	0
2000-2200	4
2200-2400	8
2400-2600	7
2600-2800	12
2800-3000	19
>3000	526
