Danny Sullivan from Google published a blogpost saying Google made 3,200 changes to its search systems last year.
Our search algorithms are complex math equations that rely on hundreds of variables, and last year alone, we made more than 3,200 changes to our search systems. Some of these were visible launches of new features, while many others were regular updates meant to keep our results relevant as content on the web changes. And some are also improvements based on issues we identified, either via public reports or our own ongoing quality evaluations.
That equals to around 8-10 changes per day to the search engine algorithm!
I wonder how many of those changes were changes to the core ranking algorithm.