None of them, really. Even among the early boomers who are on the cusp of retirement, only 25 percent know they are on target to replace at least 80 percent of their income in retirement. Even worse, though, are the numbers for the late boomers (18 percent), Gen Xers (15 percent) and millennials (17 percent). Interesting that respondents age 45 to 54 are only slightly better prepared than people who are under 30.