The Following Table Represents the Amount of Monthly Data Handled

The following table represents the amount of monthly data handled by MichNet, the University of Michigan's gateway to the Internet, sampled at six month intervals for the years 1993-1995. (The data is from the Michigan Daily, March 30, 1996, p.4.) The article also stated that the data handling capacity of the MichNet system was about 40 billion data packets per month.
$$\begin{array}{ccccccc}\text { Date } & \text { June '93 } & \text { Dec. '93 } & \text { June '94 } & \text { Dec. '94 } & \text { June '95 } & \text { Dec. '95 } \\\text { Data packets } & 1.8 & 2.2 & 4.1 & 5.0 & 7.8 & 10.5 \\\text { (millions) } & & & & & &\end{array}$$
Let $d$ be the number of data packets handled monthly (in billions), and $t$ be time in years since December, 1992. Find an equation for the best fit power function that models these data (you do not have to enter your equation). Use this equation to determine in what year the network became overloaded.