Legend block can be defined by:

• a template for element text in legend block.

Value type: String, function

• an object with settings.

Value type: Object

var chart =  new dhtmlXChart({
	...
	legend:{
			width: 75,
			align:"right",
			valign:top,
			marker:{
				type:"round",
				width:15
			},
			template:"#year#"
		},
    ...
})

or

chart.define("legend",{
			width: 75,
			align:"right",
			valign:top,
			marker:{
				type:"round",
				width:15
			},
			template:"#year#"
		});