The provided statistical chart illustrates the population of households residing in the United States, divided with respect to their yearly income in different time frames. Overall, the main participants of the competition have been those with salaries of below $25,000, between $25,000 and $49,999, and $100,000 or more, having stayed as the most populated classes interchangeably.
In 2007, the number of households gaining $100,000 or more accounted for just below 30 million, positioned as the first in rank. Descending to the second, around 27 million families had an annual salary of $25,000 to $49,999. Subsequently, households with earnings of lower than $25,000, those gaining $50,000 to $74,999, and those obtaining $75,000 to $99,999 occupied the ranks of the third to the fifth, respectively.
By the year 2011, the lower class experienced the most significant shift in the mentioned 4-year period, reaching 28 million. Furthermore, the lower-middle class exhibited a moderate increase of around 3 million. Conversely, the proportion of the upper-middle class and the affluent demonstrated a slight downfall, while the middle class retained its population throughout the period.
Moving to 2015, the upper class saw the most considerable rise, ascending from around 27 to 33 million. Additionally, the lower and the lower-middle brackets plummeted marginally, whilst the middle class maintained its consistency. The other upward trend belongs to the $75,000-$99,999 segment recovering its previous decline.