Your caloric additions per year are wrong.
We, as humans, are supposed to consume, on average, 2500 calories a day... Therefore, that would mean we would gain 260.7 pounds a year, if we went with your calculations.
We burn calories as well... So why are you factoring in weight gain without weight loss?
Diet sodas are, in fact, even WORST than non-diet sodas.
Studies have shown that people who drink diet sodas are actually fatter than people who drink regular sugar sodas.
The artificial sweeteners in "diet" sodas trick your metabolism and change your brain function, making you eat a lot more throughout the day.
Sodas are empty calories, I wouldn't recommend them at all.
But, get your facts straight before you go teaching people; you're like my mother, you think eating at night makes you fat, and that Carbohydrates aren't energy, and I could keep going on for a while.