After this year's Paris marathon, I ran the same per-minute graphs, and they match perfectly the "overall study" graphs with more than 9 million finishes in the article. I also added graphing by age category and gender. I don't want to deduce too much but I think it showed that young men are the most "competitive" (what I mean by that is targeting a specific time) since there are the clearest "goal time" peaks in the graphs.