How many Friday the 13ths occur in a year?

answer.txt

How many Friday the 13ths occur in a year?
2000: 1
2001: 2
2002: 2
2003: 1
2004: 2
2005: 1
2006: 2
2007: 2
2008: 1
2009: 3
2010: 1
2011: 1
2012: 3
2013: 2
2014: 1
2015: 3
2016: 1
2017: 2
2018: 2

Program.cs

void Main()
{
	var startYear = 2000;
	var endYear = DateTime.UtcNow.Year;
	var spookyYears = new List<(int year, int occurrences)>();

	for (var ixYear = startYear; ixYear <= endYear; ixYear++)
	{
		var spookyDaysThisYear = 0;

		for (var ixMonth = 1; ixMonth <= 12; ixMonth++)
		{
			var spookyDay = new DateTime(ixYear, ixMonth, 13);
			if (spookyDay.DayOfWeek == DayOfWeek.Friday)
			{
				spookyDaysThisYear++;
			}
		}

		spookyYears.Add((year: ixYear, occurrences: spookyDaysThisYear));
	}

	Console.WriteLine("How many Friday the 13ths occur in a year?");
	foreach (var (year, occurrences) in spookyYears)
	{
		Console.WriteLine($"{year}: {occurrences}");
	}
}