Every country defines 'urban' its own way: a few hundred residents are enough in some Scandinavian countries, while Japan sets the bar at 50,000. To finally compare like with like, the UN adopted a harmonised method in 2025 based on density and size. The verdict: about 45% of people live in a city in the strict sense, with the rest split between towns and rural areas.
That's the estimate from a WHO-led study published in The Lancet in 2024, covering the half-century since the Expanded Programme on Immunization was launched in 1974. It works out to about six lives saved every minute, mostly infants. The measles vaccine alone accounts for around 60% of those lives.
According to the World Gold Council, about 216,000 tonnes of gold have been mined in all of human history. Because gold is so dense (19.3 tonnes per cubic metre), it would fit in a cube about 22 metres on each side, roughly the height of a seven-storey building. Strikingly, about two-thirds of it has been mined since 1950.