Uncaught TypeError: Cannot read property 'length' of undefined

<!DOCTYPE html>

<html lang="en">
	<head>
		<meta charset="utf-8">
		<title>Line Chart with Multiple Lines</title>
		<style type="text/css">

body {
				background-color: white;
				font-family: Helvetica, Arial, sans-serif;
			}

h1 {
				font-size: 24px;
				margin: 0;
			}

p {
				font-size: 14px;
				margin: 10px 0 0 0;
			}

svg {
				background-color: white;
			}

path.line {
				fill: none;
				stroke: orange;
				stroke-width: 2px;
			}

.axis path,
			.axis line {
				fill: none;
				stroke: black;
				stroke-width: 1px;
			}

.axis text {
				font-family: sans-serif;
				font-size: 11px;
			}

</style>
	</head>
	<body>

<h1>CO2 Emissions by Country</h1>

<p>Carbon dioxide emissions, 1961-2010. Data not available for the entire period for all countries. Source: <a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__data.worldbank.org_indicator_EN.ATM.CO2E.KT-3Fpage-3D6&d=BQMGaQ&c=y2w-uYmhgFWijp_IQN0DhA&r=LtUave6XO55ybqGzLN8jiA&m=9lL9v1FBwp-5ssWvzQJ9ruGPO2kzydI6Tt3nwOIn070&s=ruSilEWP8l3v_3jkeIc4cR-lAbV4iY8qxdmGwMIiixc&e=">World Bank</a>, 2014</p>

//Dimensions and padding
			var width = 700;
			var height = 600;
			var margin = {top: 20, right: 10, bottom: 40, left:100};

//Set up date formatting and years
			var dateFormat = d3.time.format("Year %Y");

var bycountry = [];

//Set up scales
			var xScale = d3.time.scale()
								.range([ margin.left, width - margin.right - margin.left ]);

var yScale = d3.scale.linear()
								.range([ margin.top, height - margin.bottom ]);

//Configure axis generators
			var xAxis = d3.svg.axis()
							.scale(xScale)
							.orient("bottom")
							.ticks(15)
							.tickFormat(function(d) {
								return dateFormat(d);
							})
							.outerTickSize([0]);

var yAxis = d3.svg.axis()
							.scale(yScale)
							.orient("left")
							.outerTickSize([0]);

//Configure line generator
			// each line dataset must have a d.year and a d.amount for this to work.
			var line = d3.svg.line()
				.x(function(d) {
					return xScale(dateFormat.parse(d.Year));
				})
				.y(function(d) {
					return yScale(+d.Total);
				});

//Create the empty SVG image
			var svg = d3.select("body")
						.append("svg")
						.attr("width", width)
						.attr("height", height);

//Load data
			d3.csv("deaths_04yearsold.csv", function(error, data) {

var years = ["Year 2000", "Year 2001", "Year 2002", "Year 2003", "Year 2004", "Year 2005", "Year 2006", "Year 2007", "Year 2008", "Year 2009", "Year 2010", "Year 2011", "Year 2012", "Year 2013"];
					//Loop once for each row in data
				var bycountry = d3.nest().key(function (d) {
                      return d.Country;
                                      })
                      .entries(data);

console.log(data)
				console.log(bycountry)

//Set scale domains - max and mine of the years
				xScale.domain(
					d3.extent(years, function(d) {
						return dateFormat.parse(d);
					}));

// max of emissions to 0 (reversed, remember)
				yScale.domain([
					d3.max(bycountry, function(d) {
						return d3.max(d.key, function(d) {
							return +d.Total;
						});
					}),
					0
				]);

//Make a group for each country
				var groups = svg.selectAll("g")
					.data(bycountry)
					.enter()
					.append("g");

//Append a title with the country name (so we get easy tooltips)
				groups.append("title")
					.text(function(d) {
						return d.key;
					});

//Within each group, create a new line/path,
				//binding just the emissions data to each one
				groups.selectAll("path")
					.data(function(d) { // because there's a group with data already...
						return [ d.Total ]; // it has to be an array for the line function
					})
					.enter()
					.append("path")
					.attr("class", "line")
					.attr("d", line)
					.attr("stroke", "#FF0099");

//Axes
				svg.append("g")
					.attr("class", "x axis")
					.attr("transform", "translate(0," + (height - margin.bottom) + ")")
					.call(xAxis);

svg.append("g")
					.attr("class", "y axis")
					.attr("transform", "translate(" + margin.left + ",0)")
					.call(yAxis);

}); // end of data csv

</script>

</body>
</html>

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