It's no secret that Germany's robust economy helped bolster the eurozone and drag it out of the financial crisis. That strength also helped it to keep producing ultra-rich Germans.

Indeed, Germany has nearly as many billionaires as China, despite its much smaller population.

German billionaires saw their assets grow slightly in the past year, but wealth creation was even stronger for rich folks in a lower tier -- those with $30 million to $199 million in assets. That group saw their overall net worth increase more than 25% last year.