years has the 18% been enough to balance the budget. all those times were in the '60s. the only recent balancing came during the clinton era when growth was strong. revenue ranged from 19.5% of the overall economy to 20.6%. by bumping along with the magic average of 18%, we have built the national debt that dominates the political discussion and it's going to get worse if we stay there. the future debt we're talking and worrying about is driven by two things. health care and old people. the coming years are going to have more of both. today the elderly make up 13% of the u.s. population. by 2050, they are expected to be 20%. 20%. that means you'll need to spend a lot more on social security and medicare. meanwhile the development of new miracle treatments we hope will keep happening and that will push the cost even higher. the future turns out to be expensive. that's simply the reality of it. and opposing tax increases doesn't change that reality. there's nothing in grover norquist's pledge that stops the