Fig. 2

(a) The number of registered SRC and NSRC cases from 2007 to 2018 (the ratio of the total number of SRC and NSRC cases during the period of 2007–2012 and 2013–2018). P value was calculated by the Mann–Whitney U test (P < 0.001). b–d Time series analysis of the number of SRC (b) and NSRC (c) cases and the SRC/NSRC ratio (d) using autoregressive integrated and moving average (ARIMA) model. Raw data of time series achieved stationarity using differencing. Subsequently, autoregressive moving average model was applied to the series. The fitted model was used to forecast the incidence. The annual number of SRC cases and the SRC/NSRC ratio significantly decreased (P < 0.001 and P = 0.002, respectively). NS, not significant