How to rotate my text

How to rotate my text

I need to rotate by 180° the text. Just to read normally!!!
\documentclass[a4paper]{article}
\usepackage[margin=1cm]{geometry}
\usepackage[usenames, dvipsnames]{xcolor}
\usepackage{pstricks-add}
\usepackage{pst-all}
\renewcommand{\familydefault}{\sfdefault}

\begin{document}
\begin{pspicture}[showgrid]

\psarc(4,4){2}{0}{180}
\psset{linestyle=none,xunit=1cm,yunit=1.05cm}
\pstextpath[c]{%
\psarc(4,4){2}{0}{180}}{%
\color{red} 25\% OFP distance}

\end{pspicture}
\end{document}