Simple, data-driven graphics like this is one area where SVG really shines, I think. No need to load a JavaScript charting library if you just want some simple line charts like this. I create SVG images fairly often, and maybe half the time I find myself hand-coding them, or at least hand-tweaking them, since I enjoy the magic of seeing code turn into something visual.
An alternative if you want a bit more help with charting, without client side JS, is to use d3-shape (https://github.com/d3/d3-shape) to server-side render SVGs.