The Fédération Aéronautique Internationale (FAI) defines spaceflight as any flight above 100 kilometres (62 mi) above Earth's sea level.
The first human spaceflight occured in 12 April 1961, and as of June 17, 2018, a total of 561 people had gone to space according to that definition. This works out to about 10 people per year since 1961, but progress has not been linear or continuous.
As of December 2018, the spacecraft with the highest crew capacity to have ever been sucessfully launched on a crewed mission is the now-retired Space Shuttle, which could be configured to carry up to 10 astronauts at once, but never actually carried more than eight. In recent years, proposals have been made for a new generation of super-heavy (and beyond) spaceships capable of taking 100 or more humans to space in a single launch.
When will the 10,000th human reach space?
This question will resolve as "Yes" when credible media reports announce that a person has become the 10,000th human to reach an altitude of 100km above Earth's sea level, or if and when the same announcement is credibly made by any national or international space agency. Entering orbit is not necessary - any flight above 100km will qualify.
Persons born above this altitude (including on space stations or on astronomical objects other than Earth) are not included for purposes of this question, unless they later complete a qualifying spaceflight. Flights made from bodies other than Earth do not count.
Persons must be alive and conscious (e.g. not in suspended animation or some other state of unconsciousness or minimal consciousness) when they cross the 100km boundary, but need not survive their full mission beyond that point in order to be counted.
Finally, the number refers to the number of people to have made the flight, not the total number of flights - reflights made by the same person do not add to the total.