A recent Nielsen study across the U.S., China, India and Brazil found that money matters to Millennials and they are saving. Millennials are now one-fourth of the world population. “Upscale” Millennial, defined for the study as those 18 to 34 with Internet access and household incomes greater than the 75th percentile in their countries, represent the future of economic growth and prosperity, the study notes, as it looks at these young people country by country.