You can use stat and POSIX::strftime() to extract the mtime year. I think mtime is the proper concept, since in a way it is when the file was created in its current form.

Here's a small demo:

$ cat >foo.txt
[Ctrl-D]
$ perl -MPOSIX=strftime -e'print strftime("%Y\n",
> localtime((stat "foo.txt")[9]))'
2007
$
[download]

That gives you the year as a string, but you can add zero to that if you want it taken as a number.