How is Encryption Actually Used in Public Networks at This Moment? Has anyone done a study, assembled a snapshot, of how encryption is actually being used on the Internet at this moment?

So many companies do traffic analysis, the usage share of operating systems, etc., and one imagines that national-level agencies do this too, perhaps in incredible detail, but does any open-source information exist that quantifies the use of cryptographic hashes, asymmetric and symmetric algorithms, cryptographic libraries, etc.--and the services they provide?  

Reliable data is certainly available.

Such a study on current use could answer many interesting questions: 


  How much global message and email traffic is being encrypted all the
  way through an ISP?  With what?  How much is GnuPG being used? What cryptographic primitives are actually in decline? What services-- confidentiality, integrity, non-repudiation,
  availability, non-availability (!), authentication-- are really being
  requested, and what is their usage share?


Does a detailed, open-source (or compromised) study of global encryption use exist?
In relation to email, Google reports regularly on the use of TLS on incoming/outgoing mails through its servers, which is significant sample size given the popularity of GMail. See below.

https://transparencyreport.google.com/safer-email/overview

You can examine the data in quite some detail to see TLS usage by domain, country etc. 

They also see to have other reports on HTTPS usage etc. although I haven’t checked them out myself.