我如何在这个长表格环境中添加表格注释？理想情况下，我希望表格注释位于每页的底部。如下图所示
\documentclass[12pt]{article}
\usepackage{booktabs,siunitx, makecell, caption}
\usepackage[flushleft]{threeparttablex}
\usepackage[table, svgnames]{xcolor}
\usepackage{dcolumn}% Align table columns on decimal point
\usepackage{bm}% bold math
\usepackage[utf8]{inputenc}
\usepackage{longtable}
\usepackage{amssymb,amsmath,amsfonts,eurosym,geometry,ulem,graphicx,caption,color,setspace,sectsty,comment,footmisc,caption,natbib,pdflscape,subfigure,array,hyperref}
\usepackage{mathtools}
\normalem
\begin{document}
\begin{small}
\setlength\LTleft{3pt}
\setlength\LTright{3pt}
\begin{ThreePartTable}
\begin{TableNotes}
\footnotesize
\item [a] Euclidian Distance between output
\end{TableNotes}
\begin{longtable}{@{\extracolsep{\fill}}lccc@{}}
\caption{Frequency and percentage distributions of sample members characteristics}\\
\toprule
\midrule
\textbf{Variables} & \textbf{Category} & \textbf{Frequency} & \textbf{Percentage} \\
\midrule
\endhead
\midrule
\bottomrule
\endfoot
Total charitable donations & $>0$ & 114311 & 70.44\% \\
& =0 & 47961 & 29.56\% \\
Donation to religious charity & $>0$ & 37519 & 39.13\% \\
& =0 & 58367 & 60.87\% \\
Donation to non-religious charity & $>0$ & 58809 & 61.33\% \\
Gender & Male & 79,176 & 48.79\% \\
Age group of reference person & Less than 25 years & 7,267 & 4.48\% \\
& 25-29 years & 10 & 0\% \\
& 30-34 years & 15,058 & 53\% \\
& 35-39 years & 0& 11.506\% \\
& 40-44 years & 101 & 12.31\% \\
& 45-49 years & 10 & 110\% \\
& 50-54 years & 01 & 903\% \\
& 55-59 years & 10& 0\% \\
& 60-64 years & 1056 & 602\% \\
& 65-69 years & 8064 & 506\% \\
& 70-74 years & 7013 & 408\% \\
& 75-79 years & 0 & 4.0\% \\
& 80-84 years & 40 & 0\% \\
& 85 years and over & 2,845 & 1.75\% \\
Marital status & Married & 101,261 & 62.40\% \\
Tenure & Own a dwelling & 110,788 & 68.27\% \\
Urban & Living in urban area & 127,208 & 79.25\% \\
Year & 1997 & 105 & 110\% \\
& 1998 & 1505 & 9.036\% \\
& 1999 & 1701 & 10.051\% \\
& 2000 & 14063 & 8.97\% \\
& 2001 & 16098 & 10.29\% \\
& 2002 & 104 & 8.96\% \\
& 2003 & 6077 & 400\% \\
& 2004 & 1099 & 8.63\% \\
& 2005 & 5945 & 3.66\% \\
& 2006 & 14430 & 8.89\% \\
& 2007 & 5060 & 3.12\% \\
& 2008 & 9493 & 5.85\% \\
& 2009 & 10482 & 6.46\% \\
Region & Ontario & 21,628 & 13.33\% \\
& British Columbia & 18,587 & 11.45\% \\
& Quebec & 21,465 & 13.23\% \\
& Prairies & 45,979 & 28.33\% \\
& Atlantic & 49,570 & 30.55\% \\
& Territories & 5,043 & 3.11\% \\
Household size & 1 & 36127 & 22.26\% \\
& 2 & 51571 & 31.78\% \\
& 3 & 29620 & 18.25\% \\
& 4 & 28842 & 17.77\% \\
& 5 & 11364 & 7\% \\
& 6 or more members & 4748 & 2.93\% \\
Age of youngest child & No child & 83725 & 51.60\% \\
& 0-4 years & 202 & 109\% \\
& 5-9 years & 1072 & 072\% \\
& 10-14 years & 036 &033\% \\
& 15-19 years & 015 & 01\% \\
& 20-24 years & 6045 & 40\% \\
& 25-29 years & 607 & 30\% \\
Number of youth 18-24 & 0 & 132416 & 81.60\% \\
& 0 & 20 & 01\% \\
& o or more youth & 05 & 08\% \\
\end{longtable}%
\end{ThreePartTable}
\end{small}
\end{document}