The home page correctly lists 67 active tracks in a few locations. However, the “Use the Exercism in-browser editor” section further down the page references 70 active tracks.
It should be a smaller number than 70, as some languages cannot be edited with the browser. I tried them all 
It’s the website subtle hint calling you to create more tracks 
PR opened: Fix active track count by ErikSchierboom · Pull Request #6838 · exercism/website · GitHub (it was just a hard-coded number)