distribute	reads
0-500	0
500-800	1
800-1000	0
1000-1200	7
1200-1400	4
1400-1600	9
1600-1800	13
1800-2000	27
2000-2200	32
2200-2400	22
2400-2600	21
2600-2800	17
2800-3000	13
>3000	21
