Details of sales for the years ended December 31, 2017, 2018 and 2019 are as follows:


		2017				2018				2019
		Domestic		Overseas		Domestic		Overseas		Domestic		Overseas
		In millions of won
[Type of goods and services]
Sales of goods	￦		55,373,316		399,232		57,514,866		382,938		56,609,330		285,546
Electricity			54,649,882		—		56,842,011		—		55,939,001		—
Heat supply			205,838		—		216,117		—		220,948		—
Others			517,596		399,232		456,738		382,938		449,381		285,546
Sales related to rendering of services			186,990		164,167		176,539		216,328		222,106		186,184
Sales of construction services			92,501		3,119,683		108,586		1,633,805		110,692		1,154,224

	￦		55,652,807		3,683,082		57,799,991		2,233,071		56,942,128		1,625,954

[Timing of revenue recognition]
Performance obligations satisfied at a point in time	￦		55,373,316		399,232		57,514,866		382,938		56,609,330		285,546
Performance obligations satisfied over time			279,491		3,283,850		285,125		1,850,133		332,798		1,340,408

	￦		55,652,807		3,683,082		57,799,991		2,233,071		56,942,128		1,625,954