Based on the following excerpt, identify the most likely study design. The prevalence of psychological distress in the past 30 days increased from 16.1% in 1999-2000 to 22.6% in 2017-2018, an increase of 6.5 percentage points (95% confidence interval [CI] = 5.6, 7.3). Experimental Quasi-experimental Qualitative Systematic review Serial cross-sectional