distribute	reads
0-500	232712
500-800	21047
800-1000	2725
1000-1200	802
1200-1400	267
1400-1600	75
1600-1800	46
1800-2000	7
2000-2200	11
2200-2400	3
2400-2600	2
2600-2800	1
2800-3000	0
>3000	4
