For the most part, each year had around the same number of songs, with some difference between 1965–2000 and 2000–2015.Adding Google’s Cloud Natural Language Sentiment AnalysisOnce I had the sentiment value given by Google’s API, which is between -1 being negative and 1 being positive, I used RCharlie’s gloom index formula, which is linked at the end of this post, to take into account lyrical density, or the number of words over the duration of the song, the sentiment analysis given by the Natural Cloud API, and the valence given by Spotify’s API.Source: https://www.rcharlie.com/post/fitter-happier/For the final calculation, I normalized all the gloom index values to be between -1 and 1.The ResultsThe first visualization I made was a scatter plot of all the songs by year and their corresponding gloom index.Scatter Plot of all Songs and their Normalized Gloom Index ValueAs you can see, this does not show us much..However, once I made the box plot of all the songs by decade, it starts to look a bit more interesting.Box Plot of all Songs and their Normalized Gloom Index Value by DecadeThe averages of each decade, noted by the yellow line, appears to not change too much over this timespan..However, more current decades display a much wider range with minimums reaching as low as -5 while the high remains the same..As time goes on, the emotion displayed in popular music appears to be more polarizing because of its larger spread.Finally, I made a line plot of all the years and the average gloom index per year to see a clearer picture of what is going on.Line Plot of the Average Gloom Index Value for Each Year (1965–2015)As seen in the graph, on average songs overall have been getting sadder..With the lowest value occurring in 2015..For our final graph, we plotted these same points on a scatter plot and plotted a least squares polynomial fit line with a degree of 3 over it.Scatter Plot of all the Average Gloom Index Value by Year with Fit Line Over itConclusionThe overall trend appears to be that music, on average, is becoming sadder or more negative, but it still leans towards the positive end..There is no doubt that this is due to a multitude of factors such as, world events, the economy, and living conditions among other things, which would require analysis outside of my expertise..Although I cannot prove causality, I took the liberty of plotting the average gloom index value per year alongside some arbitrarily chosen key events in modern U.S..history.We do not know how impactful if at all, these events were in the mood of music at that time..However, the data does defend the idea that mainstream music has become sadder and more polarizing in emotion..Whether or not music like Lil Peep’s and Lil Uzi Vert continues to be the music of choice will be up to the public..Time will tell if the U.S.. More details