Bar graph added.

node_modules/d3-time/src/year.js

@@ -0,0 +1,26 @@
+import interval from "./interval.js";
+
+var year = interval(function(date) {
+  date.setMonth(0, 1);
+  date.setHours(0, 0, 0, 0);
+}, function(date, step) {
+  date.setFullYear(date.getFullYear() + step);
+}, function(start, end) {
+  return end.getFullYear() - start.getFullYear();
+}, function(date) {
+  return date.getFullYear();
+});
+
+// An optimized implementation for this simple case.
+year.every = function(k) {
+  return !isFinite(k = Math.floor(k)) || !(k > 0) ? null : interval(function(date) {
+    date.setFullYear(Math.floor(date.getFullYear() / k) * k);
+    date.setMonth(0, 1);
+    date.setHours(0, 0, 0, 0);
+  }, function(date, step) {
+    date.setFullYear(date.getFullYear() + step * k);
+  });
+};
+
+export default year;
+export var years = year.range;