distribute	reads
0-500	550192
500-800	1144872
800-1000	554151
1000-1200	440757
1200-1400	350946
1400-1600	281768
1600-1800	231558
1800-2000	193954
2000-2200	163816
2200-2400	141044
2400-2600	120974
2600-2800	101494
2800-3000	84801
>3000	441383
