distribute	reads
0-500	235041
500-800	218181
800-1000	75504
1000-1200	47918
1200-1400	32726
1400-1600	23314
1600-1800	17560
1800-2000	13395
2000-2200	10509
2200-2400	8757
2400-2600	7142
2600-2800	5982
2800-3000	5008
>3000	38149
