distribute	reads
0-500	967
500-800	948
800-1000	744
1000-1200	813
1200-1400	1033
1400-1600	1340
1600-1800	1998
1800-2000	3023
2000-2200	4561
2200-2400	6604
2400-2600	9166
2600-2800	11600
2800-3000	13981
>3000	118078
