The table shows how the radioactivity in iodine-131 decreases over time. The initial amount is 2.00 grams.
Radioactivity in Iodine-131
\begin{tabular}{|c|c|c|c|c|c|c|c|c|}
\hline Day & 1 & 2 & 3 & 4 & 5 & 6 & 7 & 8 \\
\hline Grams & 1.83 & 1.68 & 1.54 & 1.41 & 1.30 & 1.19 & 1.09 & 1.00 \\
\hline
\end{tabular}

Calculate the average rate of change in grams per day from day 4 to day 7 .
Enter your answer as a decimal, rounded to the nearest hundredth.
$\square$ grams per day