In 2007, the average was about 18 1 yuan a gram.
In 2008, the average was about 190 yuan gram.
In 2009, the average was about 2 10 yuan gram.
20 10, with an average of about 266 yuan per gram.
20 1 1, with an average of about 338 yuan per gram. Can be used as a reference
The specific price trend can be sent to you in detail.