1. You can select up to 10 curves (use the 'Check curves' button if necessary).
2. Add fitted curve: fits a curve through each time series using the lowess smoother fit algorithm.
3. Smoothing (simple moving average): for each year, the statistic is calculated using the number of deaths and the corresponding person-years at
risk over a period of 1 (no smoothing), 3 or 5 years.
4. Scale max: define the maximun scale used to display the rates (Y axis) for the arithmetic scale.