a decreasing trendP > 0.05
From 2002 to 2008, CCD proliferated with an APC of 8.256% ( P < 0.05), from 2009 to 2019, CCD developed steadily with an APC of 3.221% ( P < 0.05); and from 2020 to 2021, CCD showed a decreasing trend with an APC of -3.670% ( P > 0.05).