distribute	reads
0-500	4
500-800	2
800-1000	1
1000-1200	6
1200-1400	4
1400-1600	7
1600-1800	10
1800-2000	10
2000-2200	23
2200-2400	30
2400-2600	63
2600-2800	77
2800-3000	88
>3000	751
