You could use conditional formatting to show the difference between the positive and negative numbers/percentages. For example you could make all of the positive numbers in the “Change” and “% Change” columns green and all of the negative numbers red. This would allow someone to quickly identify numerical trends simply based on the color of the data (without actually reading the data).
The calculations and general structure are quite good for your first attempt at creating an Excel worksheet.
As for my estimated chance of winning… definately zero, since I haven’t entered. 🙂