maybe this:
\\{@JDate}
stringvar yr := RIGHT(totext(year({YourTable.YourDate}),0),2);
stringvar dy := totext(DateDiff('d',Date(year({YourTable.YourDate}),1,1),currentdate),0);
yr&dy
it will return the last 2 digits of the year and the number of days between the 1st of January and today's date.
hopefully i don't have any syntax or logic errors, if i do, my apologies in advance.