Not to rain on your parade, but a 30% correct raw score isn't that great when by randomly guessing a letter, a through e, you could get 20%. I would say that your 100%tile is likely due to the few numbers of pre urology residents taking the test.
This isn't to say that you're not smart or won't do well on future in service exams. And I honestly hope that next year you will post that your are still in the 99th to 100th percentile of year one uro residents. But, don't be surprised if your peers "catch up". I think I started in the 80-90th percentile as a year one resident (which was essentially 3 months on the uro services) and that percentile slowly went down over the years despite my raw score improving.