Final answer:
Without specific U.S. Bureau of Labor Statistics data, we can't determine the year in which educational services had 11.5 million employees.
Step-by-step explanation:
Based on the information provided by the U.S. Bureau of Labor Statistics, data reflecting employment figures for educational services for specific years are not directly stated. Therefore, without access to specific U.S. Bureau of Labor Statistics reports from the years 2005, 2010, 2015, or 2020, we cannot definitively answer the question regarding in which year the number of employees working in educational services was 11.5 million. Access to relevant labor force statistics or employment projections from the BLS would be necessary to provide an accurate answer.