What is the Real Population of Half Life 2

In a sudden burst of inspiration I try my best to come up with the best estimation for the population of the world during the game Half Life 2. I draw stuff here: Vids used: accursed farms NineFeld 00:00 - Opening 00:42 - Deaths of the seven Hour war 03:32 - World population in HL2 05:14 - Population of City 17 06:56 - Rest of the population 08:35 - Total HL2 Population 08:49 - Outro 09:26 - Credits