The proportion bar chart has the bars change colour if you select less elements. I think the bars should stay the same colour for each crime type (ex. homicide is always green, robbery is always blue)
Homicide disappears in the stacked bar chart because rates are much lower
Change the labels to be more clean (ex. use capitals, use spaces not underscores)
Add a helpText line in the sidebar to explain what the app is doing and how to use the sidebar/app
Start with only one crime checked as a default to prevent overwhelming people with data at first