Denver recorded and released approximately 300 songs, about 200 of which he composed. He had 33 albums and singles that were certified Gold and Platinum in the U.S by the RIAA, with estimated sales of more than 33 million units. He recorded and performed primarily with an acoustic guitar and sang about his joy in nature, disdain for city life, enthusiasm for music, and relationship trials. Denver's music appeared on a variety of charts, including country music, the "Billboard" Hot 100, and adult contemporary, earning 12 gold and four platinum albums with his signature songs "Take Me Home, Country Roads", "Annie's Song", "Rocky Mountain High", "Calypso", "Thank God I'm a Country Boy", and "Sunshine on My Shoulders".