howto/upgrades.md

@@ -90,6 +90,27 @@ effectively, constantly upgrading Debian. This is something we're
 hoping to fix starting in 2025, by upgrading only every other year
 (e.g. *not* upgrading at all in 2026).
 
+Another way to view this is how long it takes to *retire* a release,
+which is, how long a release lives once we start installing a the
+release after:
+
+| Releases | Date       | Milestone         | Duration     | Triggering event     |
+|----------|------------|-------------------|--------------|----------------------|
+| 8 9 10   | 2019-08-15 | N/A               | N/A          | Debian 10 start      |
+| 9 10 11  | 2021-08-26 | N/A               | N/A          | Debian 11 start      |
+| 10 11    | 2021-11-17 | Debian 10 upgrade | 27 months    | Debian 9 retired     |
+| 10 11 12 | 2023-04-08 | N/A               | N/A          | Debian 12 start      |
+| 11 12    | 2024-11-14 | Debian 11 upgrade | 37 months    | Debian 10 retirement |
+| 12       | 2024-12-10 | Debian 12 upgrade | 32 months    | Debian 11 retirement |
+| 12 13    | 2025-04-16 | N/A               | N/A          | Debian 13 start      |
+| 13       | TBD        | Debian 13 upgrade | < 12 months? | Debian 12 retirement |
+
+If all goes to plan, the bookworm retirement (or trixie upgrade) will
+have been one of the shortest on record, at less than a year. It feels
+like having less releases maintained in parallel shortens that
+duration as well, although the data above doesn't currently
+corroborate that feeling.
+
 # Minor upgrades
 
 ## Unattended upgrades