The population of Bulgaria is further on the ebb and ageing, an official from the country's statistics agency has said.

As of December 31, 2015, Bulgaria is a country of 7 153 785 people, or 1.4% of the EU's total, Magdalena Kostova, who heads the Demographic and Social Statistics with the National Statistical Institute (NSI), has pointed out at a press conference delivering the results of a population study.

This constitutes a 0.7% decrease (by 48 414) people compared to 2014. In the latter year, the population dropped by 0.4 percent.

Some 98.9% of the population are Bulgarian citizens.

Imbalances in territorial distribution of the populations are ever more notable, the NSI's findings show.

The share of citizens aged over 65 is 20.4% as of end-2015, and the average age rose to 43.3 years (having been 40.4 in 2011 and 41.2 in 2005).

The active population (over 18) decreased by 54 000, constituting 60.8% at the and of the last year.

Children under 15 were 998 206, or 14% of the total (0.1% up year-on-year), slightly below those in Germany (13.2%) and Italy (13.8%).

A declining growth rate, however, goes hand in hand with a decreasing child mortality.

The number of civil marriages increased throughout 2015 compared to the year before.

Sofia is Bulgaria's most populated region with 1 319 904 inhabitants, while Vidin, in the northwestern part of the country, is the smallest one with just 91 235, or less than in the big Sofia neighborhood of Lyulin, Kostova has announced.

As of end-2015 there were only six cities where more than 100 000 residents live (Sofia, Plovdiv, Varna, Burgas, Ruse and Stara Zagora), one down from the previous year when Pleven, now with a population of 99 628, also fell into that category.