Using \only and shifting to the right

Question

I want to use overlay in this case:

\documentclass{beamer}
\usepackage{amsmath,enumerate,amssymb}

\begin{document}
\begin{frame}{Is this a fraction or a ratio?}
    \centering
    \resizebox{0.8\textwidth}{!}{
        \only<1>{$3:4$}
        \only<2>{$12:16$}
        \only<3>{$\frac{1}{2}$}
        \only<4>{$\frac{2}{1}$}
        \only<5>{$\frac{2.5}{10}$}
        \only<6>{$\frac{10}{2.5}$}
        \only<7>{$1.2:1.6$}
        \only<8>{0.75}
        }
\end{frame}
\end{document}

Why are the numbers in each slide shifting to the right after each frame?