 The most broke generation may not be for long. Market research firm Nielsen IQ says Gen Z, born between 1997 and 2012, will have the fastest growth in spending power ahead, outspending baby boomers by 2029 and pumping out an estimated $12 trillion a year by 2030. Nielsen IQ says the average 25-year-old earns $40,000 a year, higher than other generations did at that age, and that results in more per capita spending. Michael Toscano, CBS News.