What portion of our annual deficit is financed by bonds? Compared to say, treasury notes (such as checks and printed currency), or private lending?
Unfortunately, there doesn't appear to be a single site that clearly identifies the data you seek. However, that information does appear in a couple of different sources, (in a couple of different formats):
This source from the Treasury gives a list of the values of all different types of securities auctioned off at every recent treasury auction in Excel spreadsheets
This source gives the relative holdings for domestic and foreign agents, however it doesn't break down the data into as clear specifics for tyeps of debt held.
Finally, these presentations give overviews (in the "Financing" section of each presentation) of the total value of each type of bond that was issued, and the corresponding value of each typoe that matured.
Hope that helps a bit!