Bolivia's seat of government lies at the bottom of a valley, linked to the city of El Alto, perched at around 4,000 metres, by winding, congested roads. Since 2014, an urban cable car network, Mi Teleférico, has glided over the area: ten lines and about 30 km of cable, billed by its builder as the largest network of its kind in the world. Trips that used to be long and traffic-choked now take a few minutes above the rooftops.
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.