Target-date funds continue to soar in popularity. Since their debut in the mid-1990s, they have amassed $641 billion in assets as of March 31, according to the Investment Company Institute. But target-date funds are not all alike. Take the target date 2021-2025 as an example. Going into Friday, average annual returns over the past five years ranged from a high of 14.06% for $15.5 billion T.