The bar chart illustrates changes in the number of families and their annual income across five different categories in the United States for the years 2007, 2011, and 2015.
Overall, both low- and high-earning groups saw increases in their numbers, while the statistics for mid-earning groups remained relatively unchanged.
In 2007, the highest-earning group accounted for just under 30 million households. This number dropped to 23 million in 2011 before surging to over 33 million by 2015. In contrast, the second-highest earners, which had the fewest households compared to the other groups, fluctuated slightly below 15 million throughout the entire period.
Similarly, the numbers for the third-highest income earners did not experience any significant change over the years, remaining constant at 21 million. Finally, the two lowest-income groups followed a similar trend. They started at 25 million and 23 million respectively, peaked at 28 million and 29 million, and eventually decreased to 27 million and 28 million.