Interesting plots to make

[bourque]

• Line graph of aggregate cycling distance over time
• Line graph of aggregate exercise duration over time (with option to break down by workout type)
• Pie chart of workout types
• Pie chart of workout durations
• Pie chart of instructors used by count
• Pie chart of instructors used by duration
• Line graph of cost-per-workout over time
• Heat map of workout history calendar
• Line graph of difficulty rating over time