The first lines of source code were added to Calculate Linux in 2008. If this older project has had recent activity, then this project likely is consistently delivering value, and attracts sustained effort from the community.
A longer source control history in conjunction with recent activity such as with this project, may indicate that this code base and community have enough value to hold contributors' interest for a long time. It may also indicate a mature and relatively bug-free code base, and can be a sign of an organized, dedicated development team.
Note: The source code for Calculate Linux might actually be older than the source control history can reveal. Many new projects begin by incorporating a large amount of source code from existing, older projects. You might be able to tell whether this is the case by looking for a rapid rise in the amount of code early in the project's history.