distribute	reads
0-500	408082
500-800	18667
800-1000	1270
1000-1200	322
1200-1400	62
1400-1600	15
1600-1800	11
1800-2000	4
2000-2200	1
2200-2400	1
2400-2600	1
2600-2800	0
2800-3000	1
>3000	12
