Survey | Years in recall period | Number of births in five-year period before survey | Average annual number of births |
---|---|---|---|
1995 | 1991–1995 | 4,754,595 | 950,919 |
2001 | 1997–2001 | 5,579,012 | 1,115,802 |
2006 | 2002–2006 | 6,394,207 | 1,278,841 |
2011 | 2007–2011 | 7,236,646 | 1,447,329 |