The Echo Nest has published a series of blog posts in recent months analysing the 5,000 ‘hotttest’ [sic] each year back to 1950, to see what trends emerge from the metadata. The Guardian has rounded them up into a single article, noting that music has remained about the same level of ‘valence’ over the last 63 years (that means not particularly happy or sad); that it’s been getting steadily more mechanistic and less acoustic and ‘organic’ over that time; that it’s been getting less bouncy but faster and more energetic; and – a popular argument – it’s definitely been getting louder, particularly since the rise of the CD in the late 1980s. The all-important question: has music’s danceability (a famous Echo Nest metric) risen or fallen over time? Neither. “From the time when your parents or grandparents demurely cut a rug to Elvis, all the way to Miley Cyrus’s controversial twerking at the VMA Awards last week, we’ve preferred our music to have just over average danceability,” noted The Echo Nest’s blog post on the subject.