distribute	reads
0-500	713
500-800	727
800-1000	623
1000-1200	868
1200-1400	1213
1400-1600	1819
1600-1800	2559
1800-2000	3190
2000-2200	3363
2200-2400	2996
2400-2600	2407
2600-2800	1854
2800-3000	1483
>3000	5702
