$\backslash$table$[[$Age$,$Facebook,Twitter,Instagram,Pinterest,LinkedIn$],[18-29,84,31,37,27,15],[30-49,79,19,18,24,27],[50-64,60,9,6,14,24],[65$ and older,$45,5,1,9,13]]$

Source: Data from "Table $1161-$ Social Media: Use of Social Networking Sites Among Adult Internet Users: $2013"$ in ProQuest Statistical Abstract of the United States: $2015.$

Place the data from the table in an array. $($Use Internet.txt$.)$

Determine the average of the percentages in the Twitter column. See Fig. $7\mathrm{.}68.$