Steam User Data Pulling Script

I'm looking for a C# script that pulls Steam concurrent user (CCU) data for all individual apps, similar to what SteamDB does. The script should run periodically every five minutes and output the data in JSON format (new data should be added to create a time series, not replacing previous data).

Key Requirements:
- Proficiency in C#
- Experience with data scraping and API integration
- Familiarity with Steam's data structures or SteamKit would be a plus.

Please note: The script needs to be efficient to handle the extensive data from Steam, and reliable to run on a frequent schedule without issues.