an obvious trendgold
In the situation where the data of the 9 years (from 2008 to 2016) fluctuate slightly and show an obvious trend, we used the average value of trade data from 2013 to 2016 to represent the Baseline Scenario; if it fluctuates greatly with no obvious future trend projection, the data of all 9 years is considered, and the average calculated to represent the Baseline Scenario.