Coefficient of the multivariable negative binomial regression per period using the log of population as offset and P-values from the likelihood ratio test. * = P value below 0.05 ** = P value below 0.1.

Coefficient of the multivariable negative binomial regression per period using the log of population as offset and P-values from the likelihood ratio test. * = P value below 0.05 ** = P value below 0.1.各周期下多变量负二项回归（multivariable negative binomial regression）的系数，以人口对数作为偏移量（offset），其P值由似然比检验（likelihood ratio test）计算得到。* 代表P值小于0.05，** 代表P值小于0.1。