I know you wanted to know, and so Tadeusz Ciecierski, a philosopher at the University of Warsaw, decided to compile the data. Hard to know what to make of the results, except that older journals that publish a lot (looking at you Synthese [founded 1936, publishes more than 400 articles per year] and, to a lesser extent, Philosophical Studies [founded 1950, but publishing more than 150 articles per year]) have an advantage. (Contrast Philosophical Review, which is older, but publishes only about 40 articles per year on average.) Other observations welcome.