distribute	reads
0-500	76
500-800	326
800-1000	559
1000-1200	1113
1200-1400	1756
1400-1600	2230
1600-1800	2623
1800-2000	2466
2000-2200	2263
2200-2400	2054
2400-2600	1840
2600-2800	1688
2800-3000	1545
>3000	29213
