distribute	reads
0-500	3
500-800	1
800-1000	1
1000-1200	0
1200-1400	0
1400-1600	4
1600-1800	3
1800-2000	5
2000-2200	8
2200-2400	13
2400-2600	23
2600-2800	25
2800-3000	60
>3000	823
