A reference (research paper published in 2015, focusing on proprietary
programs distributed through "app stores"):
Our analysis shows that 60% of the paid apps are connected to trackers that
collect personal
information compared to 85%–95% in free apps. We further show that
approximately 20% of the paid apps are connected to more than three trackers.
With tracking being pervasive in both free and paid apps, we then quantify
the aggregated privacy leakages associated with individual users. Using the
data of user installed apps of over 300 smartphone users, we show that 50%
of the users are exposed to more than 25 trackers which can result in
significant leakages of privacy.
http://www.privmetrics.org/wp-content/uploads/2015/06/wisec2015.pdf
