Table I.

Head size by year of insertion.

Head size, mm (%)	Total (n = 829)	2005 (n = 126)	2006 (n = 152)	2007 (n = 168)	2008 (n = 177)	2009 (n = 206)
22.225	27 (3.3)	13 (10.3)	8 (5.3)	1 (0.6)	4 (2.3)	1 (0.5)
26	108 (13)	32 (25.4)	32 (21)	22 (13)	11 (6.2)	11 (5.3)
28	352 (42.5)	61 (48.4)	81 (53.3)	69 (41)	60 (33.9)	80 (38.8)
32	190 (22.9)	10 (7.9)	20 (13.2)	51 (30.4)	53 (29.9)	55 (26.7)
36	138 (16.6)	10 (7.9)	11 (7.2)	20 (11.9)	43 (24.3)	53 (25.7)
40	14 (1.7)	0 (0)	0 (0)	4 (2.4)	5 (2.8)	5 (2.4)
52	3 (0.4)	0 (0)	0 (0)	1 (0.6)	1 (0.6)	1 (0.5)