Sarg — Squid Analysis Report Generator is a tool that allow you to view “where” your users are going to on the Internet. Sarg provides many informations about Squid users activities: times, bytes, sites, etc…
You can download; install latest version of sarg.
You need to update sarg.conf for your proxy logs details.
You can generate sarg report just by running command sarg on shell.
Once successfully completion of command you will be able to view squid reports using http.
In my case its http://192.168.100.100/squid-reports/ (192.168.100.100 is squid proxy)
You can write bash script to generate reports ; trunk old access.log to avoid regenerating old data. And to get data date-wise.