People often imagine it is far higher, but the UN puts the number of international migrants at about 300 million, less than 4% of humanity. Their number has doubled since 1990, yet their share has risen by only about one percentage point, from 2.9% to 3.7%. The vast majority of us live in the country where we were born.
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.