However, you'll find data from sources like the U.S. Census Bureau and the Oklahoma State Regents for Higher Education that will give you estimates. These estimates often range from around 25% to 35% of Oklahomans aged 25 and older holding at least a bachelor's degree. The percentage will be higher if you include associate's degrees.
To find the most up-to-date and precise figure, I recommend searching those organizations' websites directly. Look for reports on educational attainment in Oklahoma.