Final answer:
Less than 1% of the proposed amendments to the U.S. Constitution since 1879 have been successfully ratified, indicating a very rigorous process.
Step-by-step explanation:
Roughly the percentage of amendments passed since 1879 is very low compared to the number of proposals made. From 1789 through January 2, 2013, approximately 11,539 measures have been proposed to amend the Constitution, but only 33 of these obtained the necessary two-thirds vote in Congress.
Further, of these 33, only 27 amendments have been ratified. This means the success rate of proposed amendments getting through Congress and being ratified is less than 1%. The process for passing an amendment is intentionally rigorous, requiring not only a supermajority in Congress but also ratification by three-fourths of the state legislatures.
This difficult process ensured that only essential and widely accepted amendments became part of the Constitution, such as the Seventeenth Amendment, which allowed for the direct election of U.S. senators, or the Twenty-Seventh Amendment, which regulated congressional salary changes.