A multiple line chart to visualize merchant trends

Oakmark Bank's call center receives a large volume of support calls related to 5 particular merchants. They want to see the number of calls received related to these merchants over time, and understand how frequently calls related to each merchant had to be escalated.

Your job is to build a line chart showing monthly call volume by merchant, then enhance the tooltip so analysts can also see how many of those calls were escalated and what percentage of each merchant's total calls required escalation.

This helps Oakmark quickly spot merchants that may be driving higher-risk or more complex customer issues.