Help me interpret this chart please?

What do the X and Y axes mean here? (I asked the author directly but they didn't respond for some reason.)

Any thoughts on what 'Surivival Function' might mean here?

---

**War Casualties from 1800 until today, n data points**
[![War Casualties from 1800 until today, n data points](https://i.stack.imgur.com/2jzu9.jpg)](https://i.stack.imgur.com/2jzu9.jpg)