早いもので今年も既に何％が過ぎたかを示す文書

yer.tex

\documentclass[a4paper]{jsarticle}
\newcount\xxCntA
\newcount\xxCntB
\newcount\xxCntC
%% 例のMJDなアレ
\def\calcJulian#1#2#3#4{%
  \xxCntA=#2\relax \xxCntB=#3\relax
  \ifnum\xxCntA<1 \xxCntA=1 \fi
  \ifnum\xxCntB<1 \xxCntB=1 \fi
  \ifnum\xxCntB<3 \advance\xxCntB12 \advance\xxCntA-1 \fi
  \mathchardef\xxTYear\xxCntA \chardef\xxTMonth\xxCntB
  \multiply\xxCntA1461 \divide\xxCntA4
  \xxCntB\xxTYear \divide\xxCntB100 \advance\xxCntA-\xxCntB
  \divide\xxCntB4 \advance\xxCntA\xxCntB
  \xxCntB\xxTMonth \advance\xxCntB-2
  \multiply\xxCntB520 \divide\xxCntB17 \advance\xxCntA\xxCntB
  \advance\xxCntA#4\relax \advance\xxCntA-678912
  \edef#1{\the\xxCntA}%
}
\def\calcElapsed#1{%
  \calcJulian\xxSoty{\year}{1}{1}%
  \calcJulian\xxCday{\year}{\month}{\day}%
  \xxCntC\year \advance\xxCntC1
  \calcJulian\xxEoty{\xxCntC}{1}{1}%
  \xxCntA\xxEoty \advance\xxCntA-\xxSoty
  \multiply\xxCntA1440
  \xxCntB\xxCday \advance\xxCntB-\xxSoty
  \multiply\xxCntB1440 \advance\xxCntB\time
  \multiply\xxCntB100 \divide\xxCntB\xxCntA
  \edef#1{\the\xxCntB}%
}
\begin{document}
\calcElapsed\yer
早いもので今年も既にその\yer\%が過ぎてしまいました。
\end{document}