Using Yahoo Finance or any credible source retrieve the annual data, namely, short income statement, and short balance sheet, for a major corporation during the past 20 years. Provide this data and construct the graph of the sales during these years. Forecast sales in the future 3 years, and provide brief proforma statements based on best case, worst case, and normal case scenarios. Explain your work in detail, and cite all references used for development of the content.