an increasing trendP < 0.0087
As the supplementary distributional measure, the proportion of population with UIC < 100 μg/L has shown an increasing trend (β = 0.018, P < 0.0087) from 37.6% (95%CI 30.0, 46.0) in 2001–2002 to 47.7% (95%CI 41.9, 54.0) in 2017–2020.