after seeing a deluge of charts in this style I decided to make a plugin to ease your development of them
pieChart({
fillPercent: 95,
backgroundStrokeColor: "blue", //optional
foregroundStrokeColor: "green", //optional
animationRate: 5, //optional
animationTick: function(angle) { console.log("currently at "+angle)}, //optional
radius: 120, //optional
stroke: 12, //optional
container: document.getElementById('ff') //optional
});