public static String extractBuiltYear(String sourceText) {
		String[] lines = sourceText.split("\n");
		String result = "";
		for (int i = 0; i < lines.length; i++) {
			if (lines[i].contains("Approx Yr Blt")) {
				try {
					String[] subStrings = lines[i].split(" ");
					for (int j = 0; j < subStrings.length; j++) {
						if (subStrings[j].equals("Blt:")){
							result = subStrings[j + 1];
							break;
						}
					}
				} catch (ArrayIndexOutOfBoundsException e) {
					// 如果出现了数组越界，那就说明在下一行
					result = lines[i + 1].trim();
				}
				break;
			}
		}
		if (result!="" && Integer.parseInt(result) > 2050)
			result = "OT";
		return result;
	}