distribute	reads
0-500	0
500-800	199
800-1000	72
1000-1200	23
1200-1400	26
1400-1600	10
1600-1800	6
1800-2000	6
2000-2200	7
2200-2400	8
2400-2600	12
2600-2800	4
2800-3000	7
>3000	141
