distribute	reads
0-500	1388
500-800	36
800-1000	24
1000-1200	24
1200-1400	23
1400-1600	20
1600-1800	22
1800-2000	26
2000-2200	37
2200-2400	45
2400-2600	57
2600-2800	71
2800-3000	68
>3000	1270
