A large problem you’ll have is defining what “art related” means in this context. Film is clearly an art, so will you include an app that provides movie reviews? And then there is the culinary arts, so will you include an app that helps you find local restaurants? Further, if you search for any particular topic such as these in ITunes, it will list the apps and you can count them manually; it does not provide a count for you. You must decide which you will include in your count though, since searching for “Art” turns up not only titles such as “Art – Paint by number,” but also “Audio Jokes & Button Box” and “Dora saves the Crystal Kingdom.” I’d suggest you find a simple and fairly short list of types of arts and search that list in ITunes, then filter the list as you see fit. Print out some screens of the lists and manually check off the ones you’re including and you’ll get some brownie points for documenting the process you used.