Item Generation Probability

28 items to drop evenly

28 items 1/28 = 0.0357142857142857

First Item drop probability = 0.0357142857142857

Each Additional drop (2-28) probability = 0.0357142857142857 + it's relative position in the list of ALL 28 items

IE: Item (2) would be 0.0357142857142857 * 2 = 0.0714285714285714 probability

Item (27) probability = 0.9642857142857139

The last item (28) probability = 1 to prevent failures on use

In a nutshell it's basically a coin toss from 0 to 1 that falls through your probabilities until it finds a match and pops it which is why it's important that are in ascending order.