Exploding U.S. "Debt"

A simple mental exercise:

Is it true that massive sovereign debt issuance necessarily causes the corresponding interest rate of that debt to rise?  For purposes of this credit analysis type of exercise, let us ignore the national assets of countries (for example, the hydrocarbon deposits currently sitting on U.S. Federal land approaches Arabian levels of abundance, if not as easily extracted)

If so, how can one reconcile a simple stylized fact:

in 1980, total U.S. national debt was 800 Billion.

Rates at the time hovered around 20% (TWENTY percent)

in 2012, total U.S. national debt is 16 Trillion.

Rates now hover around 0% (ZERO percent)

How can this be?

Clearly, there is something going on with the notion of national rates being linked to the total debt stock in any significant fashion.  I have attempted to remind readers over and over that Sovereign Currency issuers play by a completely different set of rules than those of say, the Euro area, which must fund obligations in a currency divorced from national interest and control.

The power to issue currency is one of the primary powers of a sovereign.  This is something the Euro area will be reminded in one fashion or another.