"To look forward, we need to gauge the progress an individual has made in accumulating DC savings relative to their retirement income needs. One way would be to consider the QDIA's probability of success based on future real annuity prices -- which, unfortunately, do not exist.... [A] 20-year ladder of zero-coupon TIPS (Treasury Inflation-Protected Securities) provides the best available proxy for annuity rates. If we compare real annuity rates to the TIPS ladder, we see a 94% correlation and a small difference in the payout rate."