distribute	reads
0-500	0
500-800	15314
800-1000	6638
1000-1200	4967
1200-1400	3735
1400-1600	2952
1600-1800	2221
1800-2000	1910
2000-2200	1651
2200-2400	1334
2400-2600	1242
2600-2800	1199
2800-3000	1030
>3000	16613
