The decline in 2008 was due to oversupply in the international market. On June+10 in 5438, when Lehman happened, the financial market panicked for a while, and after all the funds were withdrawn, it caused a panic decline.

The rise in 2009 was due to the fact that after the Lehman incident, the withdrawn funds had nowhere to go, and some went back to speculate on commodities; 2. After the Lehman incident, countries injected capital into the market one after another, resulting in excess liquidity and retaliatory rise of commodities.

I am a futures trader and have a deep understanding of the market in the past two years.