distribute	reads
0-500	346776
500-800	243267
800-1000	83477
1000-1200	54789
1200-1400	38006
1400-1600	28093
1600-1800	21445
1800-2000	17281
2000-2200	13851
2200-2400	11733
2400-2600	9984
2600-2800	8617
2800-3000	7619
>3000	77127
