This year, the International Space Station turned 25 years old. A modular space station, it has now been occupied for over 23 years - a record for the longest continuous human presence in low Earth orbit. Over the years, a total of 273 people have visited the ISS, from 21 different countries.
So which nationalities can claim to have visited the space station most frequently? According to NASA data, the vast majority of astronauts that travelled to the ISS so far have been from the U.S. - 165 in total. Russia has the second-highest total at 59 while Japan comes third with 11.
