There's rich. And then there's ridiculously rich.

To fall into the first category, you should at least be a millionaire -- and even then, as the not-so-old adage goes, a million dollars doesn't go as far as it used to. To fall into the second category, you need $100 million or more.

Indeed, not only does such a category exist; it even has its own name. According to a recent report by The Boston Consulting Group, a prestigious consulting company based in Boston, households that fall into this category are known as "ultra-high-net-worth."

Thanks in large part to soaring stock prices -- the S&P 500 (SNPINDEX:^GSPC) is up by nearly 140% over the past five years -- this group is watching its fortunes skyrocket.

They held $7.5 trillion, or 5.5%, of global private wealth in 2012. By 2017, this is expected to grow to $11.6 trillion, or 6.8% of the world's private wealth.

As the report's authors note:

[T]he wealthy will continue to get wealthier globally. Over the next five years, global wealth among households with $5 million to $100 million in wealth will grow by a projected [compound annual growth rate] of 8.0 percent, compared with 9.2 percent for the ultra-high-net-worth (UHNW) segment (households with more than $100 million in wealth).

So, where do these folks call home?

The answer is: everywhere -- though they tend to prefer the more comfortable confines of the Western world -- for the time being, anyhow.

As you can see in the following slideshow, the United States leads the way with 3,016 ultra-high-net-worth households, followed by the United Kingdom with 1,001, and Russia rounds out the top 10 with 328 ultra-rich households.

John Maxfield and The Motley Fool have no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.