A cursory glance at the technology stack RealPage uses is a self-hosted portal login for client customers. One can setup a web scraper to mine the top 1 million websites over time and track the percent penetration rate. Derivatively, the portal link source contains a parameter named "propertyId" that is a sequential ID number. Tracking this number's growth over time adds a confirmatory variable as well as allowing for the calculation of client churn.
Simple.
Any questions or comments? E-mail me using the form found to the right.