The graph below shows consumers' average annual expenditure on cell phone, national and international fixed-line and services in America between 2001 and 2010

The line graph illustrates the average amount of money spent yearly on mobile phones, national and international landline phones in the US over a period of 9 years. It is clear that while the yearly spending on mobile phones increased significantly, the opposite was true for national landline phone expenditure. Also, the figure for international fixed-line service was lowest during the period. In 2001, there was an average of nearly $700 spent on national landline phones by US residents, in comparison with only around $200 each on mobile phones and international landline services. Over the next five years, the average amount poured into national fixed-line phones fell by approximately $200. By constrast, yearly spending on cell phones witnessed a significant increase of roughly $300. At the same time, the figure for overseas landline services fluctuated slightly below $300. In 2006, US consumers spent the same amount of money on mobile and national fixed-line services, with just over $500 on each. From the year 2006 onwards, it can be seen that the average yearly expenditure on mobile phones surpassed that on national fixed-line phones and mobile phones became the most common means of communication. To be specific, yearly spending on mobile phone services increased to nearly $750 in the last year, while the figure for national landline phone ones decreased to about $400 at the end of the period. During the same period, there was a stability in the figure for overseas phone calls