Table 1.

Denominator characteristics of the syndromic surveillance component of the Dutch day care-based surveillance system (2010–2013, 100 day-care centres)

	Cases		Population size mean/week (2·5–97·5 percentiles)	Incidence mean/1000 child-years (2·5–97·5 percentiles)
Study year	Total	Mean/week (2·5–97·5 percentiles)
2010–2011	483	9 (8–11)	1435 (1333–1 536)	360 (290–430)
2011–2012	517	10 (8–12)	1279 (1221–1 338)	399 (331–467)
2012–2013	829	16 (14–18)	2125 (1969–2 280)	411 (356–468)
Mean/year	610	12 (10–14)	1613 (1553–1 770)	389 (53–427)