Approximating with powers of 10

The table shown below gives the estimated number of text messages sent in the U.S. by year. **Approximately how many times as many text messages were sent in the U.S. in $2011$ as in $2005$?** Year | Text messages sent in U.S. :-: | :-: $2005$ | $118{,}000{,}000{,}000$ $2007$| $577{,}000{,}000{,}000$ $2009$ | $1{,}198{,}000{,}000{,}000$ $2011$ | $2{,}357{,}000{,}000{,}000$ [[☃ radio 1]]