Foreign adoptions peaked in 2005, USA Today reports.

The national government does not keep good statistics on domestic adoptions. But the newspaper said that many lower governments do have the information, which can be pieced together.

Changes in China that encourage adoption include a growing middle class, reduced stigma for adoptive parents and less belief in the importance of maintaining the male line.

"Better economic conditions mean more Chinese are able to bear the financial burden," said Ji Gang, director of domestic adoptions at the China Center of Adoption Affairs.

China has also begun tightening its rules for foreign adoptive parents. Earlier this year, it said that single people, those with severe weight problems and those above the age of 50.