Adapted from How can I produce a 'ring (or wheel) chart' like that on page 88 of the PGF manual?, created using the line
\wheelchart{26/cyan/Corporate, 28/orange/Plastique, 33.5/yellow/Chimique, 12.5/blue!50!red/Rhodia}

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{arrows}
\begin{document}
% Adjusts the size of the wheel:
\def\innerradius{1.8cm}
\def\outerradius{2.2cm}
% The main macro
\newcommand{\wheelchart}[1]{
% Calculate total
\pgfmathsetmacro{\totalnum}{0}
\foreach \value/\colour/\name in {#1} {
\pgfmathparse{\value+\totalnum}
\global\let\totalnum=\pgfmathresult
}
\begin{tikzpicture}
% Calculate the thickness and the middle line of the wheel
\pgfmathsetmacro{\wheelwidth}{\outerradius-\innerradius}
\pgfmathsetmacro{\midradius}{(\outerradius+\innerradius)/2}
% Rotate so we start from the top
\begin{scope}[rotate=90]
% Loop through each value set. \cumnum keeps track of where we are in the wheel
\pgfmathsetmacro{\cumnum}{0}
\foreach \value/\colour/\name in {#1} {
\pgfmathsetmacro{\newcumnum}{\cumnum + \value/\totalnum*360}
% Calculate the percent value
\pgfmathsetmacro{\percentage}{\value/\totalnum*100}
% Calculate the mid angle of the colour segments to place the labels
\pgfmathsetmacro{\midangle}{-(\cumnum+\newcumnum)/2}
% This is necessary for the labels to align nicely
\pgfmathparse{
(-\midangle<180?"west":"east")
} \edef\textanchor{\pgfmathresult}
\pgfmathsetmacro\labelshiftdir{1-2*(-\midangle>180)}
% Draw the color segments. Somehow, the \midrow units got lost, so we add 'pt' at the end. Not nice...
\fill[\colour] (-\cumnum:\outerradius) arc (-\cumnum:-(\newcumnum):\outerradius) --
(-\newcumnum:\innerradius) arc (-\newcumnum:-(\cumnum):\innerradius) -- cycle;
% Draw the data labels
\draw [*-,thin] node [append after command={(\midangle:\midradius pt) -- (\midangle:\outerradius + 1ex) -- (\tikzlastnode)}] at (\midangle:\outerradius + 1ex) [xshift=\labelshiftdir*0.5cm,inner sep=0pt, outer sep=0pt, ,anchor=\textanchor]{\name: \pgfmathprintnumber{\percentage}\%};
% Set the old cumulated angle to the new value
\global\let\cumnum=\newcumnum
}
\end{scope}
% \draw[gray] (0,0) circle (\outerradius) circle (\innerradius);
\end{tikzpicture}
}
% Usage: \wheelchart{<value1>/<colour1>/<label1>, ...}
\wheelchart{26/cyan/Corporate, 28/orange/Plastique, 33.5/yellow/Chimique, 12.5/blue!50!red/Rhodia}
\end{document}