I don't know if you're really getting an accurate portrayal by comparing two separate data points. Especially considering the economic realities (which drives budgetary decisions) of both those given years. It's probably better to take 3-4 consecutive year chunks and compare those. I'm sure the point would still be the same, but it would be a more accurate portrayal.
I'm working on a comprehensive piece breaking down what happened between our last surplus and our first trillion dollar deficit. There are a lot of factors to consider. You're right: the spending didn't increase at a steady pace over those nine years; there were specific years when it increased a lot.
Oh my, why the violence?
Not violent, just irritated that you would tell me I didn't look hard enough for a breakdown of "Other Mandatory Spending" and then link to a pie chart that lists "Other Mandatory Spending".