distribute	reads
0-500	56
500-800	36
800-1000	17
1000-1200	11
1200-1400	13
1400-1600	8
1600-1800	7
1800-2000	6
2000-2200	1
2200-2400	1
2400-2600	0
2600-2800	4
2800-3000	0
>3000	4
