http://bcnranking.jp/news/1302/130228_24917.html
(in Japanese)
The aggregated sales trend of the top four market leaders are plotted for 6 months, namely, Canon (Orange), Nikon (Yellow), Sony (Blue) and Olympus (Green). Do note that the sales of both DSLR/reflex and mirrorless types are included and added up.
As both Canon and Nikon sell mostly reflex cameras instead