distribute	reads
0-500	1599
500-800	773
800-1000	570
1000-1200	881
1200-1400	1829
1400-1600	3746
1600-1800	6762
1800-2000	10249
2000-2200	14012
2200-2400	16889
2400-2600	18647
2600-2800	18549
2800-3000	18076
>3000	67727
