According to this chart 11,322 North Americans in 2005. But that does not include those here on tourist visas. The number seems understated, but it is also a projection that is 10 years old.
http://www.inec.go.cr/A/MT/Población%20y%20Demograf%C3%ADa/Migración/Migración%20Internacional/Resultados/C0/2005/C.01%20Población%20nacida%20en%20el%20extranjero.%20Distribuc%20según%20región%20y%20pa%C3%ADs%20de%20nacimiento%20por%20sexo.xls
According to this chart Jacó has a population of 11,600.
http://www.inec.go.cr/A/MS/Censos/Censo ... s%20Demográficas/C01.%20Población%20total,%20zona,%20sexo,%20provincia,%20cantón,%20distrito.xls