Sorry I missed this post.
The graph on the frontpage of my site is generated with the Google Chart Wizard (deprecated but still in use). It allows you to create a graph from data you submit in a url query string, which they then turn into a chart live. You can see the url in the page source.
My routine is to test my typing in the morning, usually first thing. This may bias it towards slowness, but I'm consistent about it so the trend is good.
I use the typing test at
keyhero.com. No particular reason, I just like it. I do three runs with each layout, QWERTY and Minimak-12. I take the median as most representative, and that's what I graph.
Hope that clears things up.