Japanese literacy book sales spiking

Why? Prime Minister Aso quite publicly bungled a televised reading test, confusing some characters that have, well, divergent meanings.
From the AP via Yahoo News:
The Japanese leader bungled the word for “frequent,” calling Japan-China exchanges “cumbersome” instead. Another time, he misread the word “toshu” (follow), saying “fushu” — or stench — and sounded as if he [...]