We improve this part in the text. The recent movements of the government in this agricultural reform are added. Since we add the data of recent three years, another break is observed in the curve. So we also introduce the macro policy of stimulus package.
One of the most interesting issues of the paper is the political change in 2004. Perhaps, more detailed reasons of the reform would enrich the causes to promote it. Besides, the implications of this political reform are explained in the text, but more detail in these explanations would permit to understand better these changes.