distribute	reads
0-500	0
500-800	2
800-1000	0
1000-1200	1
1200-1400	0
1400-1600	5
1600-1800	8
1800-2000	8
2000-2200	11
2200-2400	19
2400-2600	40
2600-2800	59
2800-3000	75
>3000	1689
