Something causes people to ask a question. It means work for them to ask it, and work for you to answer it. The more questions the more work.
People normally query for a reason and phone calls / e-mails require action. They are an indicator of problems with a process and require resource to respond (includes both internal & external phone calls / emails – anyone who is querying the process).
To get the query % you can simply ask people how many emails / phone calls or even mail items they get a day, then compare this to the number of internal and external customers or vendors they have (customer or vendor is very broad for this – it is people who feed data into the process or take data out of it). If you can use phone and email logs if available and assume that everything is work related. Active means they are current (ie: you may have 1000 vendors for Accounts Payable but only 400 have traded in the last 12 months).