hould be treated as actual errors
						throw new Error('HTTP ' + res.status + ': ' + res.statusText);
					}
					return res.json();
				})
				.then(data => {
					histogramDiv.textContent = ''; // Clear "Loading..."

					// We'll keep track of each day with a "worstSeverity" = "ok" / "disrupted" / "down"
					var now = new Date();
					var dayStats = [];
					for (var i = 0; i < DAYS; i++) {
						var d = new Date(now);
						d.setDate(d.getDate() - i);
						var y = d.getFullYear();
						var m = Strin