For each indicator, calculate the reporting rate for each year and month The reporting rate is calculated as the number of reports divided by the number of expected reports. Here, the expected reports are calculated as the number of unique combinations of the provided columns, multiplied by the number of months and years in the data. So in this function, the data is first grouped by the provided columns, and then the number of unique combinations is calculated. Then, the data is expanded to include all combinations of the provided columns, years, and months. Then, the number of expected reports is calculated as the number of unique combinations multiplied by the number of months and years. Finally, the number of reports is calculated as the sum of the reports for each combination of the provided columns, years, and months.