You are analyzing 24 months of customer churn rates to determine whether behavior changes over time show a real trend and whether there is recurring seasonality. The monthly churn rate was 1.82%, 1.74%, 1.69%, 1.61%, 1.58%, 1.55%, 1.62%, 1.68%, 1.77%, 1.89%, 2.01%, 2.12%, 1.76%, 1.69%, 1.63%, 1.56%, 1.52%, 1.49%, 1.57%, 1.64%, 1.73%, 1.86%, 1.97%, and 2.08%, with 50,000 customers observed each month.
How would you test whether there is a statistically significant downward trend over time and a significant seasonal pattern in churn, and what would you conclude from these data?