Census 2016 shows the number of young adults in the county fell by 16.2% since Census 2011, a fall almost 10% greater than the national average
In Donegal, the numbers in the pre-school, young adults and adults age groups all fell between 2011 and 2016, while nationally only the pre-school and young adults age groups showed a decline.
The numbers in the pre-school age group fell by 15.3%, compared to a national decline of 7.0%.
Which some will see as a pointer to emigration, the numbers of young adults fell by a massive 16.2% in Donegal as against a fall of just 6.5% nationally.
People living in rural areas of Donegal are on average 2.4 years younger than those in rural areas.
The average age of Donegal's population in April 2016 was 38.5 years, an increase of 1.8 years since 2011.
Those living in urban areas of the county were on average 2.4 years younger than those in rural areas.