The number of single-income households in Korea increased to 5 million last year, taking a 27.2 percent share of the total, according to data Thursday.

Statistics Korea said the data also showed nearly half of all married couples were double-income families. The proportion of double-income families stood at 43.9 percent, which slightly increased from the previous year.

What is notable is the increase of double-income couples living separately. Officials attributed the increase to massive relocation of public institutes from Seoul and its suburbs to different regions including Sejong City.