distribute	reads
0-500	33045
500-800	25077
800-1000	9598
1000-1200	7287
1200-1400	6025
1400-1600	5004
1600-1800	4392
1800-2000	3867
2000-2200	3562
2200-2400	3366
2400-2600	3030
2600-2800	2744
2800-3000	2619
>3000	42641
