Cooper: Punk not dead cost of mifepristone and misoprostol The EBRI then looked at the impact of these scenarios on different age groups: early baby boomers, late boomers and Gen Xers. If interest rates rise back to historical averages, EBRI said 55 to 57 percent of all three groups would have enough retirement resources to cover 100 percent of their simulated retirement expenses. But these percentages fall, sometimes dramatically, under lower-rate assumptions. The conclusion is that interest rates may matter a lot to retirement outcomes.