The list of known rogue planets provided by Wikipedia is fairly short. Some are "candidates"; others "may be" red dwarfs. The two confirmed rogue planets are several times the size of Jupiter.
I understand that rogue planets can only be detected if they glow (which immediately brings the phrase "red dwarf" to mind) or if they cross the path of light emanating from a star. This makes detection extremely difficult.
The reason I ask is I'm not quite certain whether objects the size of Jupiter or smaller can even exist in interstellar space. Maybe dark matter grinds them to dust, or maybe they implode in the absence of any meaningful inertial frame - I don't know. Has anything Earth-sized been detected out there?