What percent in the US like soccer?

Answer 1

300 million people live in USA.

3 million kids between 5-19 years old play soccer.

Considering that's only children who play soccer and not anyone who just likes, then it must be around 30%

The national team in the last few years (Getting into the 2006 and 2010 World cup) has made more people aware of soccer. Also players like David Beckham playing in the MLS has made more people aware of the sport.

It's more than you think

But football (American Football), Basketball, Baseball, Ice Hockey are still more popular though.