distribute	reads
0-500	713897
500-800	302839
800-1000	90774
1000-1200	58613
1200-1400	42995
1400-1600	34660
1600-1800	29208
1800-2000	25634
2000-2200	23180
2200-2400	20522
2400-2600	19482
2600-2800	18000
2800-3000	16653
>3000	276039
