Table 2. General characteristics of study participants.

		2020				2021			Total
		September	October	November	December	January	February	March
Participants		3,837	4,006	3,438	3,152	3,056	2,711	3,034	23,234
Sex	Male	1,933	1,986	1,732	1,534	1,512	1,359	1,497	11,553
	Female	1,904	2,020	1,706	1,618	1,544	1,352	1,537	11,681
Age, years	≤19	99	114	118	103	95	81	71	681
	20–39	317	408	311	320	281	213	295	2,145
	40–59	829	928	753	715	694	586	665	5,170
	60–79	1,770	1,771	1,556	1,413	1,352	1,226	1,389	10,477
	≥80	822	785	700	601	634	605	614	4,761
Region	Special wards of Tokyo	2,415	2,653	2,337	2,157	1,995	1,741	2,026	15,324
	Tama area	1,422	1,353	1,101	995	1,061	970	1,008	7,910