Feature request: netflow like rate limiting

[HaanJde]

I'm using dnstap in a reasonable busy setup (avg. 16K, max. 19K queries/second) and my processing / storage setup (Graylog+Elasticsearch) can barely cope.
Since we are using this for statistical analysis only, we would love to have a feature with which we can say from the command line "send on only 1 in x queries".
Somthing like:
-L 1:1000
I hope you can consider implementing this feature.
Thanks for your efforts and keep up the good work.