As baby boomers approach retirement and millennials fill the void, the shift could lead to a decrease in average earnings, making that statistic a less useful indicator of the strength of the labor market, Bloomberg reported.


That means that Federal Reserve Chair Janet Yellen's focus on wages to help gauge the strength of the job market could need fine-tuning. The dynamic could be one reason for the sub-par wage growth that Yellen says shows "significant slack" in the job market.


A similar dynamic is influencing the unemployment rate, which is dropping faster than predicted, in part because of the retirement of baby boomers.


People who are 25 to 34 years old will make up 22.5 percent of the workforce by 2022, compared with 21.6 percent in 2012. The share of the country's oldest employees, those over the age of 55, will increase to 25.6 percent from 20.9 percent. But people who are 45 to 54 years old - who are typically in their best earning years - will drop by 3.3 percent.


Another story on today said a survey found that Americans between 18 and 29 years old are three times more likely to keep their long-term investments in the form of cash rather than in the stock market.


The survey was done by, whose chief financial analyst told CNNMoney that losing out on investment returns could hurt millennials down the road.