Re: Where to start...
To be fair, I was thinking more historically, but even more recent wars have had something of an impact - according to the ever-reliable Wikipedia, up to 80 million people died "[including] 19 to 25 million war-related famine deaths". That was 3-4% of the entire world population at the time.
Then too, it was significantly worse at a country level - some (e.g. Poland) suffered 15%+ casualties.
Any which way, war sucks.