According to Billboard and Nielsen Music, individual track sales took a hit in 2016, dropping from 113.9 million units sold in 2015 to 87.5 million units in 2016. Even with the 26.4-million decline, two artists managed to release singles that soared over the 1-million mark: Florida Georgia Line’s “H.O.L.Y” (1.37 million) and Tim McGraw’s “Humble…