How can I calculate the following?
The number of people who are registered to vote
The number of people who are eligible to vote
As a whole and for specific people in an option group and is viewed according to the control selection.

I have a form that allows me to view how many of our people are eligible to vote, registered to vote and who actually voted. They can use a combo box that allows them to choose which election they would like to see the results for. The problem is that we don't have historical data so the numbers that are picked up for the eligible and registered fields are coming from a query that pulls up information from the beginning of time. So the numbers for those two fields are the same for every election and we want to know how many people are eligible and registered to vote for each election per counselor and as a whole.

So as an attempt to capture historical data in the future I have created a snapshot of what we have right now and when the next election comes around we will have another snapshot of the results for that particular election and so on. But I'm not sure how I'm going to calculate how many people are registered and eligible to vote per election, per counselor and as a whole all while pointing to the appropriate table.

This was my original expression but I don't know how to make it count according the control selection and in correspondence to the appropriate table. Right now there is only one but will be more in the future.
=DCount("[Participant SSN]","[ElectionFrmQuery]"," ([Mailing County] like'*Travis*')")

As I type I realize that this whole process seems a bit complicated so if there are other suggestions to simplify this I'd appreciate it, if not any solutions or guidance for the above will also be greatly appreciated.