Set up auditing for Impala and use a tool to analyze it (or do it yourself). I have feed these audit logs to Cloudera Optimizer and Splunk (this requires Splunk and SPL knowledge). Both will give you your answers to this and quite a bit more.
Honestly, to just get your answer you should be able to read the audit files and use basic unix tools like grep, awk, cut, sort, uniq, etc. to get tables names and the frequency.
