The graph provides a comparison of the number of households by their annual salary in the US in three years 2007, 2011 and 2015.
Overall, the distribution remained unchanged in terms of the ranking of income brackets in the year 2007 and 2015. However, there was a fluctuation in the places when the peak shifted from the tail to the head of the pattern.
At the beginning of the examined period, households who had the highest income with more than $100000 per year accounted for the highest number, at south of 30 million. They were followed by those earning $25000-$49999 and less than $25000, at nearly 27 million and exactly 25 million respectively. In addition, the figure for those with $50000-$74999 were lower, with over 20 million of families. The final salary bracket was the lowest, at under 15 million.
In the period from 2007 to 2015, despite a slight decline in 2011 by almost 2 million, the highest income group saw a significant growth to 33.5 million. Meanwhile, there was an increase in the number of families with the income of $25000-$49999 and less than $25000, making them rank first and second in 2011. Nonetheless, they returned to their positions in 2015. On the other hand, the rest stay almost stable during the period from 2007 to 2015.