The question is, how much data NSA accesses in a single request. The official rules have changed but the "two hop" rule permits the agency to recover metadata from about 25,000 phones with a single request, according to 2016 Stanford study.

https://spectrum.ieee.org/nsa-can-legally-access-metadata-of...

In addidition to the official request NSA infiltrated links to Yahoo, Google data centers worldwide.

http://www.washingtonpost.com/world/national-security/nsa-in...

https://news.ycombinator.com/item?id=6641378