Why does the color of The Shirt change from year to year?

The tradition of changing the color of The Shirt each year began with the first two Shirts created in 1990 (a green shirt for the Michigan game and a navy shirt for the Miami game). The Shirt has changed colors each year since then with the exception of years 2002-2004, where it remained green three times in a row. The Shirt has most commonly been shades of blue and green with a few exceptions. Though the color of The Shirt typically changes from year to year, the exact color is kept confidential until the unveiling in April.