Patrick Lagacé has some numbers from Influence Communication about letters to the editor, and which Quebecers get their letters published most often: Sylvio Le Blanc and Jeannot Vachon.
The study also shows The Gazette prints more letters to the editor than any other publication, and more than 60% more than the next-largest, Le Soleil. The paper prints a handful of letters every day, and last year redesigned its opinion section to give more space to letters (and less space to editorials).
UPDATE: Lagacé has a response from Vachon.