This charts shows the split ratios (time for the second half of the race, divided by the first) for 7,190 London Marathon 2016 finishers as obtained from strava athletes data. The data is rendered using a combination of d3 and d3fc components.
Updated missing url https://unpkg.com/d3/build/d3.min.js to https://cdn.jsdelivr.net/npm/d3@12.10.3/d3.min.js
https://unpkg.com/d3/build/d3.min.js
https://unpkg.com/d3fc@12.0.0/build/d3fc.min.js