distribute	reads
0-500	0
500-800	2
800-1000	0
1000-1200	2
1200-1400	4
1400-1600	0
1600-1800	2
1800-2000	11
2000-2200	7
2200-2400	14
2400-2600	20
2600-2800	24
2800-3000	21
>3000	75
