Uber and Lyft drivers protested low pay this week. Here are the cities where their earnings have fallen the most.

• Uber and Lyft drivers staged a strike and protests around the world this week to call attention to their low pay.
• JPMorgan Chase Institute, a think tank inside the bank, recently published research on the gig economy.
• The group found that average revenues had changed wildly for drivers, depending on their city.
• While drivers in some cities saw their revenues increase between 2013 and 2018, many in other cities, like Bridgeport Connecticut, saw them fall dramatically, as much as 87%.

Drivers for Uber and Lyft staged protests and work stoppages in cities around the world this week to protest falling pay on the ride-hailing platforms.

Both companies said they're actively working to ensure drivers are paid fairly, but in many cases, average pay has fallen quite a bit.

The JPMorgan Chase institute, an economic think tank inside the US' largest bank, set out to quantify exactly how much - or how little - members of the gig economy are making in select locations.

"We use geographic and temporal variation to explore these dynamics in more detail in order to get a better understanding of the viability of the transportation and leasing sectors of the Online Platform Economy as a potential source of income for participant families," the group of analysts said in their published report. "We explore variation in characteristics of the Online Platform Economy over five years across 27 metropolitan areas."

Read more: 15 cities where Uber and Lyft drivers make the most money

The data show that average monthly revenue declined for drivers between 2013 and 2018, with analysts adding that their findings "fully account for the secular trends in driver revenues, even as participation shares shifted across metro areas."