For reference that's about the same number of people as the population of Switzerland, although probably a lot less neutral.
The info was picked up on Steam's stat page (via NeoGAF/Polygon) and saw the service hit 8,020,834 concurrent users at around 7pm UK time on Sunday June 29, breaking the previous seven million record set in December 2013. The boost here's probably from people having a last weekend check even though the sale's actually still on today. Safe to say it's hit its peak for time being though.
This post originally appeared on Kotaku UK, bringing you original reporting, game culture and humour with a U from the British isles.