The appointment letter was stamped March 4th, and I received it at my college address on the 19th (it may have been held for a number of days due to the fact that last week was Spring Break and no mail is delivered during breaks).
I have a few ideas as to why I received an appointment this year but not last year. First, last year I applied with an ACT score of 26. I retook it two more times and it brought my superscore to a 28. I had a pretty decent amount of leadership and service during high school but I continued that during my first year here at college as well. I was accepted into a Scholars program, joined my Resident Hall Council, spent Spring Break in New Jersey for a service trip, and I was even chosen as a Resident Advisor ("Head of Floor") for the next academic year. My CFA scores also improved. Lastly, last year I received a nomination from my Senator and this year I received in from my Congressman (less people to compete against).
Overall, I truly don't know what the exact factor was. I spoke with an admission counselor last year and was told that I had a very strong application aside from my ACT scores (this might have been proven false with my first semester college GPA which was a 4.0).