distribute	reads
0-500	881033
500-800	320719
800-1000	127437
1000-1200	93729
1200-1400	71796
1400-1600	57833
1600-1800	48202
1800-2000	41080
2000-2200	36205
2200-2400	32358
2400-2600	29753
2600-2800	26941
2800-3000	25104
>3000	852144
