@Another one: for any single country it is a lot, but the site is pretty much global. About 50% Americans but a lot of visitors from UK, Canada, Australia and many other countries. No money invested apart from the hosting costs and my time.
@ProThoughts: It's a dedicated server but I run one or two much smaller sites on it as well. Shared hosting would never be able to handle those traffic levels. The dedicated server had a big slowdown at our traffic boom.