It depends on whether you are referring to Christian, “classical liberal” libertarianism in the Hayekian sense, or Jewish “libertine” libertarianism in the Rothbardian sense. Around 10-12% of Americans identify themselves libertarian – although the number that consider themselves Rothbardian is not something we have trustworthy survey data for, the activism of the rothbardian libertine minority outweighs is negligible political influence.
https://www.quora.com/What-proportion-of-people-in-various-countries-are-libertarian