When are the days getting longer the fastest?

We're way past the winter solstice, and approaching the equinox. The sun is noticeably staying up later and later every day, which raises an obvious question: when are the days getting longer the fastest? Intuitively I want to say it should happen at the equinox. But does it happen exactly at the equinox? I could read up on all the gory details of this, or I could just make some plots. I wrote…