distribute	reads
0-500	72466
500-800	24573
800-1000	10868
1000-1200	8572
1200-1400	6899
1400-1600	5410
1600-1800	4396
1800-2000	3684
2000-2200	3027
2200-2400	2567
2400-2600	2148
2600-2800	1760
2800-3000	1464
>3000	9314
