Blogger still hosts millions of blogs on blogspot and custom domains, and every one of those sites has the same problem: adding a small piece of live data — how many people are reading, which countries visit, where people click — usually means installing a gadget you'll have to maintain, update and trust.
Nothing to install. Blogger's own HTML/JavaScript gadget takes raw markup, which is all this needs — and unlike a theme edit, a gadget survives changing your theme. Every widget below is one snippet, pasted in once. Pick one and the page tells you the exact menu path for Blogger, the gotchas, and what to do if you're on an older theme or a page builder.