distribute	reads
0-500	6
500-800	1
800-1000	1
1000-1200	3
1200-1400	5
1400-1600	4
1600-1800	7
1800-2000	12
2000-2200	22
2200-2400	31
2400-2600	40
2600-2800	30
2800-3000	57
>3000	320
