distribute	reads
0-500	283323
500-800	414913
800-1000	167146
1000-1200	126893
1200-1400	101925
1400-1600	86146
1600-1800	75450
1800-2000	67727
2000-2200	61842
2200-2400	56094
2400-2600	51241
2600-2800	46889
2800-3000	43623
>3000	878851
