distribute	reads
0-500	211640
500-800	178050
800-1000	85838
1000-1200	73957
1200-1400	65736
1400-1600	60056
1600-1800	55035
1800-2000	52075
2000-2200	48734
2200-2400	46204
2400-2600	44113
2600-2800	41865
2800-3000	39703
>3000	661993
