change "timeformat_old" from 6 months to 1 year

[Fourhundred Thecat <400thecat gmx ch>]

Hello,

I am using different date formats for "timeformat_recent" and
"timeformat_old":

  [Misc]
  timeformat_recent=%b %e  %H:%M
  timeformat_old=%Y %b %e  %H:%M

which gives me nice, clean dates, where new files are immediately
distinguished from older ones:

       Sep  3  15:13
  2016 Mar 10  19:57

that works great, except that "timeformat_old" is used for files 6
months or older.

I would like to change it to 1 year or older, so that for newer files
(less than one year), I don't see the year.

How can I do it ?