Table 2 Distributions of birth dates by groups.

Group	Birth Months
(Year of Birth)	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	χ2
Elite 1	147	140	112	78	72	83	51	38	37	37	23	16	309.57 **
(2005-2006)		399			233			126			76		293.78 **
Elite 2	486	376	342	273	261	211	213	163	132	124	108	79	719.06 **
(2008-2009)		1024			745			508			311		641.57 **
Amateurs	70	60	57	51	60	44	39	55	59	35	30	31	38.42
(2006-2007)		187			155			153			96		29.09 **

** p < 0.001