thaks25, ideally you want to choose a statistic or trend that's related somehow to your post-grad career goals. This is a chance to show the impact you want to have in your career -- in other words, how does what you want to change about this statistic relate to the change you want to drive or the impact you want to have in your career once armed with the MBA? This is also a chance for you to explain why this industry/issue (and likewise your goals) matter to you. Of all the things you could do with your life & career, why is this area your passion?
And it goes without saying that you also want to have very specific post-grad career goals. They want to see the title you're aiming for in the ST & LT as well as your 2-3 target firms. Or, if you plan to start a business, you'll need to be ready to explain what problem you'll be solving or what unmet need you'll be filling as well as how you plant to differentiate yourself from the competition. And then, like I said, what you plan to DO in those goals (whether working for a company or starting your own) will be ideally be related to this statistic or trend.
And then...you'll be all set up to make your argument for why you need the MBA (and why SAID in particular) to get there. Although save that for another time - that's not something to include in this essay. But your career goals do form the basis for your "why MBA"/"why our school" argument.
Let me know if that helps!