Surprised at how little the rankings changed over five years? I am not. In my experience, pages that rank well tend to continue to rank well over long periods of time. After five years, our page still ranks well.
What affects the rate at which rankings change?
The durability of a page’s ranking depends on the rate at which new content comes out on that topic.
Changes to the ranking algorithm are real, but the much bigger SEO trends are the “SERP features,” such as featured snippets, maps and videos. There’s just a lot more stuff showing up in search results these days.