http://chartpark.com/wti.html
https://www.bloomberg.co.jp/news/articles/2016-05-06/O6QLRR6S972C01
http://woman.excite.co.jp/article/lifestyle/rid_Techinsight_20160505_259330/
https://www.bloomberg.co.jp/news/articles/2016-05-05/O6Q52D6JIK3201