distribute	reads
0-500	0
500-800	0
800-1000	1
1000-1200	0
1200-1400	5
1400-1600	2
1600-1800	11
1800-2000	28
2000-2200	43
2200-2400	113
2400-2600	214
2600-2800	288
2800-3000	506
>3000	18819
