Add years on the dateTime object:
DateTime baseDate = new DateTime(2000, 2, 29);
Console.WriteLine("Base Date: {0:d}\n", baseDate);
// Show dates of previous fifteen years.
for (int ctr = -1; ctr >= -15; ctr--)
Console.WriteLine("{0,2} year(s) ago:{1:d}",
Math.Abs(ctr), baseDate.AddYears(ctr));
Console.WriteLine();
// Show dates of next fifteen years.
for (int ctr = 1; ctr <= 15; ctr++)
Console.WriteLine("{0,2} year(s) from now: {1:d}",
ctr, baseDate.AddYears(ctr));