distribute	reads
0-500	143
500-800	63
800-1000	45
1000-1200	48
1200-1400	55
1400-1600	108
1600-1800	178
1800-2000	356
2000-2200	524
2200-2400	837
2400-2600	936
2600-2800	1205
2800-3000	1646
>3000	16002
