表 4. Incidence rate divided by circles in Chengdu in 2012–2020.

2012–2020成都市手足口病分圈层发病率

Region	Number of cases	Incidence (/105)*
First circle: The former central administrative area of Chengdu city; Second circle: An area integrated into the central administrative area of Chengdu in 2017; Functional area: An economic function area merged into the central administrative area of Chengdu in 2017; Suburban cities: Some counties and towns in the suburbs of Chengdu. Details of the circles are available in the sources. * The difference in incidence between circles was statistically significant (χ2=13804.176, P<0.05).
First circle	93963	219.64
Second circle	100083	237.92
Functional area	24572	194.80
Suburban cities	71033	138.36