code: function(elements) {
  			if (!elements.length) {
  				return false;
  			}
  
  			var i, len;
  			var x = 0;
  			var y = 0;
  			var count = 0;
  
  			for (i = 0, len = elements.length; i < len; ++i) {
  				var el = elements[i];
  				if (el && el.hasValue()) {
  					var pos = el.tooltipPosition();
  					x += pos.x;
  					y += pos.y;
  					++count;
  				}
  			}
  
  			return {
  				x: Math.round(x / count),
  				y: Math.round(y / count)
  			};
  		}
docs: Average mode places the tooltip at the average position of the elements shown
  @function Chart.Tooltip.positioners.average
  @param elements {ChartElement[]} the elements being displayed in the tooltip
  @returns {Point} tooltip position