The provided bar graph illustrates the distribution of households in the United States based on their annual income in the years 2007, 2011, and 2015.
Overall, it is evident that there was an upward trend in the number of households with the lowest and highest annual incomes, while the middle-income households experienced fluctuating trends over the period.
In 2007, approximately 25 million households had an annual income of less than $25,000, while around 30 million households earned $100,000 or more. The number of households earning between $25,000-$49,999 was around 35 million, which slightly increased to nearly 37 million in 2011 before decreasing to 30 million in 2015. Similarly, households with an annual income of $50,000-$74,999 were around 30 million in 2007, remained stable in 2011, and then decreased in 2015.
In contrast, the number of households earning $75,000-$99,999 increased from around 20 million in 2007 to 25 million in 2015. Notably, the number of households with an annual income of less than $25,000 remained relatively stable at around 28 million in 2011 and 2015, while the number of households earning $100,000 or more increased to nearly 30 million in 2015. It is noteworthy that these income categories maintained consistent proportions over the three-year period.