function calculateAnnualChange(diff, diffYears) {
const result = [];
for (let i = 0; i < diff.length; i++) {
const countryCode = diff[i].country_code;
const value = diff[i].value;
const yearDiff = diffYears.find(item => item.country_code === countryCode).year_diff;
const annualChange = value / yearDiff;
result.push({ country_code: countryCode, annual_change: annualChange });
}
return result;
}