This repository insights graph is available in public repositories with GitHub Free, and in public and private repositories with GitHub Pro, GitHub Team, and GitHub Enterprise Cloud. For more information, see "About repository graphs" and "GitHub's products."
The Code frequency graph displays the content additions and deletions for each week in a repository's history.
Accessing the Code frequency graph
On GitHub, navigate to the main page of the repository.
Under your repository name, click Insights.
In the left sidebar, click Code frequency.