How much debt does the US Treasury sell?

For a given fiscal year, how much debt does the US Treasury issue in the form of bonds? Is simply a function of demand and all revenues acquired become part of the budget? Is it tied to the deficit in a for that year? If it is the former, how can we ever balance the budget? If it is the latter, does the government not sell debt instruments in surplus years?

Thanks for your help,
Rob

As much as it needs to roll over from prior years, plus enough to fund the current year’s deficit.

No. Bond sales aren’t considered revenue, either for the government or for a business.

During surplus years, outstanding debt is rolled over, less any amount which can be retired by the surplus.