distribute	reads
0-500	1
500-800	0
800-1000	1
1000-1200	0
1200-1400	1
1400-1600	0
1600-1800	2
1800-2000	3
2000-2200	3
2200-2400	1
2400-2600	3
2600-2800	6
2800-3000	3
>3000	16
