The number of married couples has tumbled more than 30 percent over the past two decades, with the average age of first marriages soaring, a report showed Tuesday.

According to the report by the Seoul Metropolitan Government, the city saw a total of 71,695 marriages last year, down a whopping 33.5 percent from 107,821 in 1992.

Of them, 62,208 cases involved a husband in their 20s and 30s in 2012, a 40 percent plunge from 103,672 in 1992, the report showed.

Seoul citizens were also found to wed later in life, with the average age of first marriages rising by more than four years from 28.5 in 1992 to 32.4 last year among men and from 25.6 to 30.2 for female citizens, according to the report.

This has led to an increased number of single people who are of childbearing age. In 1980, some 50.3 percent of male citizens aged 25-29 remained single, but the figure soared to 90.7 percent in 2010, with the rate among women jumping from 19.7 percent to 80.2 percent.

Of those aged 30 to 34, 58.9 percent of male and 41.7 percent of female citizens remained single in 2010, striking a stark contrast to 30 years ago when less than 10 percent of citizens did not tie the knot.

"The notion of marriage was affected by a combination of diverse social circumstances, including women's active participation in society and difficulties in childbirth and child-rearing amid the protracted economic downturn," a city official said.

The city also saw a decline in the sheer number of women of childbearing age over the past 20 years. The number of female citizens aged 25 to 39 came to 1.6 million in 2012, a 19.3 percent fall from 1992, and the number of newborn babies last year stood at around 94,000, less than half the number of 198,000 in 1982.

Asked about the reasons for not having a child, some four out of 10 citizens cited economic burdens for child-rearing, and some 20 percent expressed difficulties in leading work and family life at the same time.

"The government needs to find ways to boost the low birthrate, as the current marriage and child-bearing trend indicates that concerns over the low birthrate will not be easily gone anytime soon," the official said. (YNA)