Question: In what year did Langfang have a population of 4,358,839 people while Yichun, Heilongjiang have a population of 1,148,126 people?

Context paragraphs:
Yichun, Heilongjiang: Yichun () is a prefecture-level city on the Songhua river in Heilongjiang province, People's Republic of China.  The city is separated from Russia by the Amur River and has an international border of 246 km .  At the 2010 census, Yichun has a total population of 1,148,126 while 729,202 people live in 15 districts separated by forests.  The greening rate of Yichun is up to 83%.  The nickname of Yichun is Lindu ().

Yilan County, Heilongjiang: Yilan County () is under the administration of Harbin, the capital of Heilongjiang province, People's Republic of China.  It is more than 240 km to the east-northeast of central Harbin.  Its county seat, which is also called Yilan (Yilan Town, "Yilan zhen"), is located near the confluence of the Mudan River (formerly known as the Hurka River) with the Sungari.  The easternmost county-level division of Harbin City, it borders Fangzheng County to the southwest, Tonghe County to the west, as well as the prefecture-level cities of Yichun to the north, Jiamusi to the northeast, Qitaihe to the southeast, and Mudanjiang to the south.

Dongsheng Subdistrict, Nancha District: Dongsheng Subdistrict () is a subdistrict of central Nancha District, Yichun, Heilongjiang, People's Republic of China, about 75 km southeast of the city proper of Yichun.  , it has 6 residential communities (社区) under its administration.

Yichun Lindu Airport: Yichun Lindu Airport (IATA: LDS, ICAO: ZYLD) is an airport serving the city of Yichun in northeast China's Heilongjiang Province.  It started operations in August 2009, and is capable of serving 142,000 passengers a year.  It incorporates a runway measuring 2300 m and is located in a forest approximately 9 km from downtown Yichun.

Suihua: Suihua () is a prefecture-level city in west-central Heilongjiang province, People's Republic of China, adjacent to Yichun to the east, Harbin, the provincial capital, to the south, Daqing to the west and Heihe to the north.  It has 5,418,453 inhabitants at the 2010 census, of whom 877,114 lived in the built-up ("or metro") area made of Beilin District.

Dongsheng Subdistrict, Yichun District: Dongsheng Subdistrict () is a subdistrict of Yichun District, in the eastern outskirts of the city proper of Yichun, Heilongjiang, People's Republic of China.  , it has 3 residential communities (社区) and 4 villages under its administration.

Hongxing District: Hongxing District () is a district of the city of Yichun, Heilongjiang province, People's Republic of China.

Langfang: Langfang (), is a prefecture-level city of Hebei Province, which was known as Tianjin Prefecture until 1973.  Hebei province was renamed Langfang Prefecture after Tianjin became a municipality and finally upgraded into a prefecture-level city in 1988.  Langfang is located approximately midway between Beijing and Tianjin.  At the 2010 census, the population of Langfang was 4,358,839, of whom 868,066 lived in the built-up ("or metro") area made of Guangyang and Anci districts; its total area is around 6417.28 km² .  Langfang borders Baoding to the southwest, Cangzhou to the south (both prefecture-level cities of Hebei), Beijing to the north and Tianjin to the east.  Sanhe City and Dachang Hui County are now conurbated with Beijing, so that they form part of the same built-up area.  Langfang is the smallest prefecture-level city of Hebei Province by land area.

Jiayin County: Jiayin County () is a county of eastern Heilongjiang province, People's Republic of China.  It is under the jurisdiction of the prefecture-level city of Yichun and the county seat lies on the southern (right) bank of the Amur River.

Cuiluan District: Cuiluan District () is a district in the west of Yichun, Heilongjiang province, People's Republic of China.

Supporting paragraphs: Langfang Yichun, Heilongjiang
Answer: 2010