distribute	reads
0-500	46
500-800	0
800-1000	3
1000-1200	0
1200-1400	2
1400-1600	5
1600-1800	5
1800-2000	10
2000-2200	6
2200-2400	7
2400-2600	13
2600-2800	20
2800-3000	11
>3000	143
