I made a visualization of when and how many times a country appeared in the MARC Visual Material collection.
Using the MARC Visual Material collection, I use all the countries name as keywords and group all the records by country and the year they appeared.
Sketch: https://marc-countries.glitch.me
Code: https://glitch.com/edit/#!/marc-countries
Some findings:
Most appeared country: United States, of course. However, the most frequent time the US appeared was between 1970 – 1990. Canada follows as the second most frequent country that appears.
Other more frequently appeared countries and years: Germany – 1973; Japan – 1988; China – 1977.
India appeared a lot more often after 2007.
To be improved: I wish to make the countries in the botton cluster more legible.