What year is referenced in relation to the median age of the population in the initial statistic provided?

The correct answer is based on the historical context of demographic data collection, specifically regarding the median age of the population. In many countries, especially those that conducted census data around the early 20th century, 1911 is notable as a census year. During this period, significant movements in population dynamics were documented, reflecting the changing social landscapes. The median age data from that time is critical for understanding population trends and the implications on society, such as family structures and workforce demographics. Other years listed may have their own relevance in demographic studies, but 1911 is particularly significant when discussing median age statistics in the context provided, making it the most accurate reference year for the initial statistic mentioned.