Rabbit Population Tracking

As a good practice, I keep track of how my rabbits are doing over time. As the say, if you aren't measuring, you aren't managing.
Of course, what's a bunch of data if you aren't making a fun visual? Here is my graph after having two kindles yesterday morning.
How do you keep track of your herd?

I’ve kept a pet rabbit or two for years. I’ve considered breading rabbits over the, years but never taken the plunge. I working on my animal care PEP is going to be the fine nudge I need to get started breeding rabbits. I hadn’t thought about tracking the rabbit population. Now I can incorporate this practice from the beginning. Thanks!

What program do use for this data?

I'm sure there is a smarter way but, here's how I do it. In a spreadsheet, each rabbit gets their own line with a starting and ending date.
To make a graph there is another column for dates, and a formula for counting how many are in the herd on that day. I sure hope someone sees this and points me at the smart way to do it.