Here are the latest statistics available for average (mean) U.S. Net Worth Distribution Statistics by Age. You can see the trend over time in the first chart and view the raw numbers in the bottom chart.
From the timeline, it appears you must have been over 35 years old to participate in an increasing mean (average) net worth. Group ‘Less than 35′ stayed the same over the last 20 years! This clearly gives visual proof that the wealth-building years are generally age 35 and after, and even more so for age 45 and later. The age group ’55 – 64′ increased their net worth most rapidly between 1998 and 2004 but lost ground between 2004 and 2007. Age groups ’45 – 54′ and ’75 and older’ all increased at very similar rates. The ’65 – 74′ group had the highest overall increase.