This is basic representational and strategic numeracy for the purposes of this project.
The population of the U.S. is a little over 300 million.
A state is small (and therefore its citizens are overrepresented in the Senate, Electoral College, and amendment power) if it has less than 2% of the U.S. population, or less than about 6 million people.
A state is large (and its citizens underrepresented) if it has more than 2% of the U.S. population.
About one-third of states are large, and two-thirds are small.
About two-thirds of U.S. citizens live in large states (and the territories and D.C.); one-third of citizens live in small states.
According to Article V, ratification is by three-fourths of state legislatures or conventions.
If we insist on using Article V to make Article V, the Senate, or the Electoral College proportional, a whole bunch of small states would have to vote against their own interests in relinquishing disproportionate political power. It has not happened.
If, on the other hand, we vote by citizen, it is a lot easier. Two-thirds of citizens can vote themselves more power – proportional to their numbers. No voting against personal interests is required.