Fun with Google Ngram Viewer, pt. 2.
The chart below delineates references to five library classification schemes (Dewey Decimal Classification, Library of Congress Classification, Universal Decimal Classification, Colon classification, and Bliss Bibliographic Classification) in books published between 1950 and 2008. As the search terms are relatively uncommon in the Google Books corpus, I’ve smoothed the data by using 5-year rolling averages. The terms are case-insensitive.
Classifiers won’t be surprised to see DDC and LCC dominating today. Published interest in other schemes has almost been extinguished in the English-speaking world. But the early data hints at a radically different perspective on library classification two generations ago, when faceted schemes looked like realistic alternatives to the two (mainly) enumerative schemes now ascendant.
In the late 1950s, there were more printed references to UDC than to any other scheme; the same was true of Colon classification in the early to mid 1960s. Interest in BC peaked in the 1980s. No other classification scheme generates statistically meaningful data.
The fall-off in discussion of individual schemes has not been as precipitous as that for library classification generally. Updates to DDC and LCC continue to be published regularly, maintaining a background hum of references.