distribute	reads
0-500	965077
500-800	1181142
800-1000	540856
1000-1200	417876
1200-1400	332430
1400-1600	270437
1600-1800	223140
1800-2000	187670
2000-2200	161531
2200-2400	140460
2400-2600	122189
2600-2800	108955
2800-3000	98630
>3000	1468790
