The graph below shows Twitter use by age group in the USA between 2010 and 2013

The line graph illustrates how Twitter was used by different age groups in the United States in a three-year period, from November 2010 to May 2013. The overall trend was clearly one of an increase, and the youngest age group (18 – 29 years old) contributed the most to the total use of Twitter.
One of the most striking features in the graph is the rapid growth of use in the 18 – 29 age group. Starting with only 14% in November 2011, the proportion of this age group doubled at the end of the period, making itself the most popular age group using Twitter. The figure was lower when it comes to middle-aged users. Followed by the wild fluctuation throughout the period, the percentage of users in this group finally reached its peak at 18% in May 2013, which was approximately threefold compared to the initial figure.
Unlike those younger users, 65+ age group was shown to nearly remain the same percentage of its Twitter users throughout the period, at only about 5%. The 50 – 64 age group, however, experienced a slight increase in users of this social media site, with an increase of 5% from 2011 to 2013.
In conclusion, from November 2011 to May 2013, Twitter saw a drastic increase of users in almost all age groups, with the most noticeable one being shown in the proportion of users aged between 18 and 29.