distribute	reads
0-500	872927
500-800	366740
800-1000	152239
1000-1200	114195
1200-1400	90529
1400-1600	74198
1600-1800	62409
1800-2000	53507
2000-2200	46452
2200-2400	41183
2400-2600	36747
2600-2800	33280
2800-3000	30530
>3000	732090
