Percentage of films made in each genre by year

The plot below shows the percentage of movies produced over the years in the different genres (from this source, thanks to Sundar for sharing):

As a proper scientist, I had to question the source of the data used to produce the plot.
First I think the numbers come from the IMDB website, which may be biased towards american films, so that the statistics may not be representative of the movie production in the rest of the world.

By the way this other plot below shows you where movies are made in the world (from this source):

Then, the IMDB website have its own definition for genres, but that might be OK. My only comment is that 'short' might not be considered as a genre, as a short movie can actually be of any genre (romance, drama, SF...).
The format of the plot can also be discussed as it shows relative percentage, so if the production of one genre drops, it looks like all other genres peak at the same time.

Now we can move on to the analysis of the plot. What are the main features?

• The Western genre died at the end of the 70's (I have recently read an interesting article about this in the magazine IMPACT, at the occasion of the release of the remake of True Grit)
• The SF and Horror genres have slowly but steadily increased over the last half-century, to the detriment of Western (very well illustrated metaphorically in Toy Story)
• The production of porn exploded in the last forty years, but there could be a bias in the numbers...
• Short movies are almost always the relatively most produced 'genre', with some slow fluctuations over time
• Documentaries, shorts and porns shared the characteristic of beeing the cheapest genres to produce, and in the last 20 years more and more people have access to the means of producing their own movie in those genres.
• There are more and more Animation films, following the progresses in technology I guess.
• People always like to laugh and cry, as is shown by the constantly large percentage of comedies and dramas
• Action movies were very popular in the 80's (didn't need the plot to know that)
• There is a sharp increase of the production of crime movies around 1969. It is very well explained on the website reddit. In summary: "[...] because in the American industry, prior to the MPAA ratings system was the Hays code, which was far more restrictive. It was a system of censorship under which you could not even depict two people in bed together -- not having sex, just on the same bed -- portray priests or authority figures as foolish, or let the bad guy win in a movie. Because there were no ratings restricting movies to adults, all movies had to be okay for everyone. The era between the collapse of that system and the rise of the current blockbuster model is called Postclassical Hollywood and the spike in "crime" on this graph is because as soon as that old restrictive system collapsed, people went crazy for all the gritty realistic stuff like Midnight Cowboy and Straw Dogs that they weren't allowed to make before".