In this image you can see that the way movies are certified/ rated changes to a more specified way. Instead of Approved and Passed somewhere in the 1960's a more complex rating system was created with PG, PG-13, R, and Unrated films.
There is a spike in films being released between 1910 - 1920, as well as a rapid decrease. During this time the Great Depression occurred which could have had an impact on the amount of films being produced.
From the two images above it is interesting to see an definite increase in war genre movies. This probably has to do with the fact that we were in a war period in the Middle East and that there was a spiked interest in creating war movies about the past too.