distribute	reads
0-500	499471
500-800	21620
800-1000	1032
1000-1200	191
1200-1400	31
1400-1600	10
1600-1800	5
1800-2000	1
2000-2200	1
2200-2400	1
2400-2600	0
2600-2800	0
2800-3000	0
>3000	5
