function fillYearField() {
	const numberOfYears = 100;
	const currentYear = today.getFullYear();
	const startYear = currentYear - numberOfYears;

	for (let i = startYear; i <= currentYear; i++) {
		const option = document.createElement('option');
		option.value = i;
		option.textContent = i;

		i === currentYear && option.setAttribute('selected', 'selected');
		yearField.appendChild(option);
	}
}
Fill the year field with the last 100 years.