distribute	reads
0-500	1202495
500-800	516023
800-1000	115854
1000-1200	59965
1200-1400	34844
1400-1600	22400
1600-1800	15179
1800-2000	11324
2000-2200	8430
2200-2400	6968
2400-2600	5460
2600-2800	4660
2800-3000	3948
>3000	44750
