Romeo Santos has sold out four shows at New York's Madison Square Garden in a single month. His 2012 solo debut, "Formula Vol. 1," was the top-selling Latin album of the year, according to Nielsen SoundScan, producing five No. 1s on Billboard's Latin Airplay chart and tying a record set by Enrique Iglesias. He's had seven No. 1s on Latin Airplay, including the recent "Propuesta Indecente" (Indecent Proposal), which topped the chart last October. Nonetheless, outside of the Latin music world, he's mostly unknown.