How much EXIF information is tracked by photo sharing sites?

How much EXIF information is tracked by photo sharing sites?
http://regex.info/exif.cgi

I often post photos to photo-sharing sites, whether for the
purpose of social networking (pinterest, facebook, etc)
or for Usenet posts (tinypic, flickr, etc) or for personal
sharing (iCloud, dropbox, google drive, etc).

The EXIF, as you know, can reveal exactly where and when
the photo was taken, and even what camera was used, and, of
course, the time and date, etc, the combination of which could
easily reveal intensely personal information.

When I DOWNLOAD those pictures, generally (always?) the
EXIF information seems to be stripped out.

But ... how much of that personal EXIF information is retained by
the web site (and used for their possibly nefarious purposes)?