Create new API endpoints for Visualizations

Three visualizations will be added for our site which is the following: a bubble chart of types of attractions, a map showing how many universities are in each state, and a bar graph showing how many major cities are in each state.

To accommodate for these visualizations, three new API endpoints must be created on the backend. The API endpoints needed are the following: An endpoint that returns how many attractions there are of each type, an endpoint that returns how many universities each state has, and an endpoint that returns how many major cities each state has. This task is estimated to take 30 minutes to complete.