Population

The term population refered to the total number of individuals inhabiting a certain location.

Total population
In 1791, Hempel noted the planet Earth's population to be "eight hundred million, give or take." (AUDIO: The Sword of the Chevalier)

In 2006, the Ninth Doctor claimed Earth's population to be five billion. (TV: World War Three)

On Christmas Day 2009, a total of 6,727,949,338 people were temporarily transformed into the Master Race, constituting almost the entire human population of Earth save Donna Noble and Wilfred Mott, whom were spared the transformation. (TV: The End of Time)

As the Twelfth Doctor noted, Earth's population was seven billion by 2017. (TV: The Lie of the Land)

By the year 2472, Earth's population was 100 billion. (TV: Colony in Space)

In the year 200,000, the Ninth Doctor noted Earth's population as being 96 billion. (TV: The Long Game)

Specific locations
In 2012, Henry van Statten noted Salt Lake City, the city nearest to his Vault, to have a population of one million. (TV: Dalek)