Because whoever generated that chart decided to only include these. The raw data is avaiable for anyone to play around with here in csv: https://data-analysis.fedoraproject.org/
It looks like to me that the chart is coming from the ublue project, so if you are a tech person, you can fork their countme repo and modify it to your needs.
I was in your shoes too. I liked monkeytype but it became boring after a month, then I found https://www.typelit.io/
If you like to read novels as I do, you will love it. You basically have to retype books as you read them.