I want to have some text aligned to the center of the top or bottom of an ellipse. I've tried
\documentclass[border=0.5]{standalone}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{mathtools,amsmath}
\usepackage{tikz}
\usepackage{pgfplots}
\pgfplotsset{compat=1.15}
\usetikzlibrary{decorations.text}
\begin{document}
\begin{tikzpicture}
\draw (0,0) ellipse [x radius=3, y radius = 2];
\draw (0,0) ellipse [red,x radius=4, y radius = 2.66];
\draw(0,0) ++(-3.5,0) [decorate,decoration={text along path, text={This text should be between the eppelipses in the bottom half}}] arc [start angle=-160, end angle=-10, x radius=3.5, y radius = 3];
\draw(0,0) ++(-3.5,0) [decorate,decoration={text along path, text= {This text should be centered and in the top half}}] arc [start angle=160, end angle=10, x radius=3.5, y radius = 4];
\node at (0,0) {center text};
\end{tikzpicture}
\end{document}
I get