In the last three blog posts at ehbritten.org Marc Demarest delves into a new research tool that addresses precisely the kinds of questions discussed by Joe, Govert, June, and others in a recent thread.  Having seen a few of his search results, from the POV of the Church of Light I wanted to see how Hermetic/Hermeticism and astrology, the two keywords most relevant to us, compare to Theosophy and Spiritualism, two source traditions:

http://books.google.com/ngrams/graph?content=theosophy%2Cspirituali...

Adjectival forms yield a different picture in which Hermetic is clearly on the rise:

http://books.google.com/ngrams/graph?content=theosophical%2Cspiritu...

Madame Blavatsky and Mary Baker Eddy seesaw for predominance but finally converge from about 1970 onward:

 http://books.google.com/ngrams/graph?content=Mary+Baker+Eddy%2CMada...