The line graph on each station popup shows the number of bikes available at a station over the previous 72 hours. Data points are omitted when the count doesn't change, creating an effect that draws attention to periods of higher use.
The bar graph on each station popup shows the average usage per day of the week in the last 30 days. Usage is measured as the number of bikes removed from a station throughout the day. This metric is an approximate derrived from data collected.