I was thinking:
in my mind, Postgres 9.6 was associated with 2016, and "6" at the end of
both the version and the year always helped me memorize the release year.
Memorizing is important when you deal with many databases running different
versions of Postgres – this gives you perspective how old the version is.
And over last 10 years, the release cycle is pretty stable, one major
version per year. So if the upcoming version were 26 instead of 19, and
next year's were 27, it would be easier to understand how current this
version is.
Nik