過去50年的統計值http://blog.xuite.net/wellsli/003/195425007-%E5%BE%9E%E9%81%8E%E5%8E%BB50%E5%B9%B4%E9%87%91%E5%83%B9%E7%9A%84%E8%B5%B0%E5%8B%A2%E5%88%A4%E6%96%B7%E6%9C%AA%E4%BE%8612%E5%B9%B4%E7%9A%84%E9%BB%83%E9%87%91%E5%83%B9%E6%A0%BC
