distribute	reads
0-500	307466
500-800	18192
800-1000	1890
1000-1200	539
1200-1400	184
1400-1600	76
1600-1800	30
1800-2000	23
2000-2200	12
2200-2400	9
2400-2600	11
2600-2800	5
2800-3000	7
>3000	48
