check this link and content
http://www.symantec.com/business/support/index?page=content&id=TECH183109
After a client has installed the product, we will have our first chance to review the files that are installed and running on the machine. We will typically send between 300 kilobytes and 1 megabyte of data during the first few weeks. In some extreme cases, we may send as much as 3 megabytes of data depending on the amount of software installed and actively in use on the machine. Submissions will take place when the machine is idle, but queries will be scattered across the period of time as our detection technologies analyze files for the first time.
16. What is the average daily/weekly bandwidth used for reputation lookups (submissions) during steady-state operation of my typical PC (a few weeks after installation)?
Once the initial round of submissions and queries have completed, the amount of data will be fairly minimal. New submissions and queries will only be sent when new files arrive on the machine, either through downloads or installation of other software. You can expect approximately 4 kilobytes of data for each new executable file placed on the machine to be sent to Symantec. As mentioned above, our data shows that the average machine performs 1-2 reputation lookups per day. This equates to approximately 4-8 kilobytes of transmitted data per day.