# Only one bullet per subsection in header [duplicate]

I want to have in my header of my presentation only one bullet for each subsection. Although several questions handle similar problems, I was not able to solve my problem so far.

Here is to code I use:

\documentclass{beamer}
\usepackage[english]{babel}
\usepackage[T1]{fontenc}
\usepackage[latin1]{inputenc}
\usetheme{Singapore}

\begin{document}
\section{Text1}
\subsection{Text1.1}
\frame{Text1.1.1}
\frame{Text1.1.2}
\frame{Text1.1.3}
\subsection{Text1.2}
\frame{Text1.2.1}
\frame{Text1.2.2}
\subsection{Text1.3}
\frame{Text1.3.1}
\section{Text2}
\subsection{Text2.1}
\frame{Text2.1.1}
\frame{Text2.1.2}
\frame{Text2.1.3}
\subsection{Text2.2}
\frame{Text2.2.1}
\frame{Text2.2.2}
\subsection{Text2.3}
\frame{Text2.3.1}
\frame{Text2.3.2}
\frame{Text2.3.3}
\end{document}


At the moment I get for each slide in a subsection a bullet. What do I have to change so that I get only one bullet for each subsection? I would be very happy about some help!

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