"The Great Gatsby," originally published in 1925, only became a huge hit when the Pentagon distributed it free to soldiers during WWII. Eyeballing the upslopes around 1943, perhaps the War had something to do with Joyce and Kafka's growing popularity too.

Look, the arts do go through changing fashions, of course.

Sometimes older artists whose work was ignored or forgotten come to seem very important - J.S. Bach in music and Johannes Vermeer in painting, for instance. In literature I'd guess Laurence Sterne became more important to academics during the PoMo ascendancy, because Tristram Shandy lends itself very well to PoMo analysis.

As for modernist writing, its not surprising there should be a wave of interest which later abated. At one time it seemed that Finnegans Wake represented the ultimate fate of the novel. Now it doesn't.

I'm guessing, if you looked at music, you'd see academic writing about Arnold Schoenberg following the same trajectory. There was a time when Serialism seemed to be the music of the future, so academics wrote about it a lot. Now Serialism seems dead. So academic interest has probably waned too.

At the same time, interest in Schoenberg's contemporary, Stravinsky, has probably gone up. His mid-period Neoclassical scores (written during the 1920s to the 1940s) used to be despised by critics, unlike his Modernist early works (written up to just after the end of World War One). But later, his Neoclassical music came to seem like PoMo before the fact. So academics got more interested in it. And once Minimalism became the established style of new classical music, that reinforced Stravinsky's importance. You can hear how, say, Steve Reich's "Tehillim" is influenced by Stavinsky's "Les Noces". But there's no Schoenberg (or Second Viennese School) influence on Minimalism at all. Minimalism is a pretty conscious raised third finger to Serialism.

The point is, it's the work of writers, artists and composers that forces the pace of academic discourse. Music journals used to be filled with articles by Allan Forte and George Perle about "pitch class sets" and "combinatoriality" in Atonal and Serial music. This was because the most important living composers - Boulez and Stockhausen - were both profoundly influenced by Serialism (more Webern than Schoenberg in fact). Now Minimalism has taken over that writing just feels less relevant.

I wonder if perhaps one factor is simply that the number of authors who were "worthy" of an article or of research has broadened. That is, rather than their stock having fallen it's that their impact has been diluted. The cultural studies aspect of literature studies, especially in the last 20 years, makes for a far larger pool of works to be studied.

Incidentally, based on my purely anecdotal experiences (I'm a PhD student in English Lit at a larger midwestern university), I would say that close reading is indeed coming back into fashion. There seems to be a "theory-exhaustion" and a pull back to the fundamentals.

I wonder if perhaps one factor is simply that the number of authors who were "worthy" of an article or of research has broadened. That is, rather than their stock having fallen it's that their impact has been diluted. The cultural studies aspect of literature studies, especially in the last 20 years, makes for a far larger pool of works to be studied.

That's an interesting point I hadn't thought of. If we borrow a metaphor from ecology, the population of Modernists saw the growth of some other population (those who benefited from "expanding the Canon"), which is slowly crowding them out of their niche.

Did the expanding Canon start around 1955 - 1965? If not, we just change the newly invading population to something that did increase during that time.

I think that Dickens would have been a better control than Austen -- Austen was popular with many modernists (e.g. F.A. Leavis). Sir Walter Scott might be good too. It would be interesting to see if they revived. (Tennyson, Browning, Carlyle, and Matthew Arnold almost certainly didn't).

I think we're looking at late Modernism, though, not really post-modernism. At a certain point there wasn't much new to say about J, P & K.

Of course arts go through changing fashions, but a great work will also withstand the test of time. And, one would expect that a lot could be said about a text early on, and less and less over time. I also note that Austen's popularity has been creeping up -- this may, however, be a demonstration of the increased numbers of people studying literature, which would also affect the numbers for Proust, Kafka, and Joyce. I would like to see a graph showing the number of scholars entering the field over the same period. I would also be interested to see what has been replacing the Big Three (perhaps with their decreasing popularity, they need a bailout?).

As far as Kafka is concerned, he has popularity for all ages of academic. The reason is that he anticipated many features of the 20th century, including the dominance of bureaucracies and their oppressive nature. He anticipates Existentialism, and the attempts by the postmoderns to turn us all into isolated automata. In many ways, then, he is a transitional writer, and thus a tragedian of sorts.

Joyce has such a high curve because he was a difficult writer, and that just gives scholars a lot to work with. I wold be willing to bet that you see something similar with Heidegger, for the same reason. In fact, it might be fun to see the trend lines for various philosophers, to see their popularity over the 20th century. May I suggest: Nietzsche, Heidegger, Kant, Hegel, Marx, Sartre, Derrida, Wittgenstein, Plato, and Aristotle.