Visualizing +/- change week-to-week

The nonprofit group I'm working with operates 50+ preschool centers in multiple counties. As they serve nearly 3,000 kids each day, tracking enrollment numbers is imperative to their business model.

I have an Excel document that has the enrollment percentage for each classroom in each center. It's in the following format:

A1 - Date
A2 - Center Name
A3 - Classroom Number
A4 - Enrollment

Example:

1/2/2012 ABC Center 36 107.14%
1/2/2012 ABC Center 37 120.83%
1/2/2012 ABC Center 38 95.83%
1/2/2012 ABC Center 39 95.83%
1/2/2012 XYZ Center 100 90.63%
1/2/2012 XYZ Center 101 87.49%
1/2/2012 DGT Center 14 34.10%
1/9/2012 ABC Center 36 107.14%
1/9/2012 ABC Center 37 120.83%
1/9/2012 ABC Center 38 95.83%
1/9/2012 ABC Center 39 95.83%
1/9/2012 XYZ Center 100 90.63%
1/9/2012 XYZ Center 101 87.49%
1/9/2012 DGT Center 14 34.10%
1/16/2012 ABC Center 36 107.14%
1/16/2012 ABC Center 37 120.83%
1/16/2012 ABC Center 38 95.83%
1/16/2012 ABC Center 39 95.83%
1/16/2012 XYZ Center 100 90.63%
1/16/2012 XYZ Center 101 87.49%
1/16/2012 DGT Center 14 34.10%


... And it goes on, through more than 7,000 datapoints (rows). The dates are fixed every seven days; enrollment information is captured weekly. And data may end arbitrarily for one center at any given point in time because the center or classroom may close, a new center may be created, etc.

I need to be able to analyze how enrollment has changed over time from week-to-week. But rather than just reading through thousands of rows of data, I need to make it more of a visualization. Perhaps a timeline or something, that shows the +/- change from the previous week, and preferably with a chart showing the actual overall and individual center trendlines in a configurable period of time.

How best might this be done? I don't know the first thing about pivot tables, and I am not at all opposed to investing money into plugins or other data modeling software if it can't do what I need it to do. I haven't done any serious VBA work in a long time. I'm sure it'll come back to me fairly quickly, but I don't have the time to write the code and our in-house software developer is consumed on other projects. If that's my only option, I'd prefer a third party plugin or other modeling software if there are options for one.


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