i am not sure what that has something to do with it
you need x doctors per 1000 people, x hospitals, x nurses and so on
1 person causes on average y dollars, euros whatever healthcare expenses per year
so it is basic math to calculate the average cost for a healthcare insurance - depending on how many people pay into it
it has zero to do with the size of the country or population
it becomes more complicated when - like in the US - you let "insurance" companies, big pharma and lobbyists run wild
despite of all problems they still have with it: Germany has a pretty good system with a mix of government regulated (and mandatory) healthcare insurance (which are not allowed to make profits - gasp!) plus private insurance companies for those that qualify for them
and no one will say that you get bad healthcare in Germany (just watch Dr. House, they use Siemens Medical MRTs

).
And when you can do it for 80 million people, you can do it for 300 million too - once again: basic math