Here is how I get all the interface traffic. (try cut past this to terminal)
:foreach id in=[/interface find] do={
:local output "$[/interface print stats as-value where .id=$id]"
:put "$output"
}
For more information see my script that I do use to get all kind of data inn to Splunk:
http://forum.mikrotik.com/t/tool-using-splunk-to-analyse-mikrotik-logs-4-0-graphing-everything/153043/1
Example:
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