distribute	reads
0-500	1233577
500-800	126287
800-1000	13566
1000-1200	3802
1200-1400	1186
1400-1600	424
1600-1800	182
1800-2000	98
2000-2200	84
2200-2400	48
2400-2600	37
2600-2800	39
2800-3000	25
>3000	297
