Looking for easy way to compare data over time - pivot?

I have data for different service providers and the number of calls they take over different quarters of the year. I'd like to compare q1 from one year to q1 of another year. I keep thinking I should be able to use a pivot table, but when I look at tutorials, it doesn't seem to be the right kind of data set. Is there a way to filter or pull data from a single table and compare them, e.g., look at % increase or decrease from that same time period the year before? I've attached a table with call data. All pivot table tutorials that I've found relate to sales performance, but the data are too different from mine for me to be able to understand if that's the way to go.

In plain English, here's what I want to do:
at any given time, take data from a cumulative report, pluck 2 time periods and compare them. I know that I could set this up by formula but I'm looking to avoid creating yet another spreadsheet.

Thanks,
Sue

You are looking for comparables from year to year per center? If so a pivot table is not your best resource. I would use formulas. Attached, I have changed the organization of your data to best explain the comparables per center. I know this is not exactly what you were looking for, but I hope it helps.

Thanks Dafodil11 and Mandy11. Both responses are very helpful.