Formatting financial statements in commn size can eliminate inherent bias' that usually occurs whenever analyzing companies of differing sizes. Common size also allows for the analysis of a company over various time periods rapidly, e.g. revealing what percentage of sales is cost of goods sold and how that value has changed over time.
OGE Energy Corp, https://www.oge.com/wps/portal/SignIn/!ut/p/z1/04_Sj9CPykssy, SIC Code: 4911, ELECTRIC SERVICES
View Financial Statements Report for OGE Energy Corp