distribute	reads
0-500	166958
500-800	7031
800-1000	793
1000-1200	295
1200-1400	106
1400-1600	45
1600-1800	33
1800-2000	18
2000-2200	17
2200-2400	5
2400-2600	11
2600-2800	10
2800-3000	2
>3000	36
