(I made the graphic) - Unfortunately, there's obviously no data on the pitches that VCs see. There could be ways to halfway infer it - for instance, founder age tends to be different by industry (https://modeanalytics.com/benn/reports/a43fb710b2ef). If you look at how one VC's investments in one industry differs from overall investments in that industry, you might be able to somewhat control for the different pitches VCs see. But without more complete data, drawing any conclusions beyond things like "YC founders are young" is tough.
On a related note, here's something else I wrote that looks into whether or not older founders perform better: http://blog.modeanalytics.com/are-experienced-founders-bette...