Table 1.

Numbers of children enrolled for the study

Year	Male (n)	Female (n)	Total (n)
2000	4,578	4,202	8,780
2001	21,512	20,350	41,862
2002	34,705	36,178	70,883
2003	117,742	112,852	230,594
2004	140,835	132,235	273,070
2005	140,447	128,913	269,360
2006	44,395	40,585	84,980
2007	41,858	38,802	80,660
2008	38,482	36,219	74,701
Total (n)	584,554	550,336	1,134,890