distribute	reads
0-500	3
500-800	0
800-1000	1
1000-1200	2
1200-1400	2
1400-1600	6
1600-1800	9
1800-2000	12
2000-2200	9
2200-2400	17
2400-2600	6
2600-2800	18
2800-3000	15
>3000	61
