[Question] How much memory is reserved for cute kitten pictures?

In my social circles, I frequently tell a joke making fun of the awful lot of cute kitten pictures available on the internet (“somewhere in the world, a whole server farm is doing nothing but storing pictures of cute kittens”). Joking apart, there are thousands of data centers around and the world’s total data storage capacity is measured in Zettabytes.

How much of this memory do you think to be actually occupied by cute kitten pictures? What could be an effective way to make a Fermi estimate?