Sonja's credit card has an APR of [tex]$21 \%$[/tex], calculated on the previous monthly balance, and a minimum payment of [tex]$2 \%$[/tex], starting the month after the first purchase. Her credit card record for the last 7 months is shown in the table below.
\begin{tabular}{ccccccc}
\hline
\begin{tabular}{c}
End of \\
month
\end{tabular} & \begin{tabular}{c}
Previous \\
balance
\end{tabular} & \begin{tabular}{c}
New \\
charges
\end{tabular} & \begin{tabular}{l}
Payment \\
received
\end{tabular} & \begin{tabular}{l}
Finance \\
charges
\end{tabular} & \begin{tabular}{c}
Principal \\
paid
\end{tabular} & \begin{tabular}{c}
New \\
balance
\end{tabular} \\
\hline
1 & [tex]$\$[/tex] 0.00[tex]$ & $[/tex]\[tex]$ 700.00$[/tex] & [tex]$\$[/tex] 0.00[tex]$ & $[/tex]\[tex]$ 0.00$[/tex] & [tex]$\$[/tex] 0.00[tex]$ & $[/tex]\[tex]$ 700.00$[/tex] \\
2 & [tex]$\$[/tex] 700.00[tex]$ & $[/tex]\[tex]$ 0.00$[/tex] & [tex]$\$[/tex] 14.00[tex]$ & $[/tex]\[tex]$ 12.25$[/tex] & [tex]$\$[/tex] 1.75[tex]$ & $[/tex]\[tex]$ 698.25$[/tex] \\
3 & [tex]$\$[/tex] 698.25[tex]$ & $[/tex]\[tex]$ 0.00$[/tex] & [tex]$\$[/tex] 13.97[tex]$ & $[/tex]\[tex]$ 12.22$[/tex] & [tex]$\$[/tex] 1.75[tex]$ & $[/tex]\[tex]$ 696.50$[/tex] \\
4 & [tex]$\$[/tex] 696.50[tex]$ & $[/tex]\[tex]$ 0.00$[/tex] & [tex]$\$[/tex] 13.93[tex]$ & $[/tex]\[tex]$ 12.19$[/tex] & [tex]$\$[/tex] 1.74[tex]$ & $[/tex]\[tex]$ 694.76$[/tex] \\
5 & [tex]$\$[/tex] 694.76[tex]$ & $[/tex]\[tex]$ 0.00$[/tex] & [tex]$\$[/tex] 13.90[tex]$ & $[/tex]\[tex]$ 12.16$[/tex] & [tex]$\$[/tex] 1.74[tex]$ & $[/tex]\[tex]$ 693.03$[/tex] \\
6 & [tex]$\$[/tex] 693.03[tex]$ & $[/tex]\[tex]$ 0.00$[/tex] & [tex]$\$[/tex] 13.86[tex]$ & $[/tex]\[tex]$ 12.13$[/tex] & [tex]$\$[/tex] 1.73[tex]$ & $[/tex]\[tex]$ 691.29$[/tex] \\
7 & [tex]$\$[/tex] 691.29[tex]$ & $[/tex]\[tex]$ 0.00$[/tex] & [tex]$\$[/tex] 13.83[tex]$ & $[/tex]\[tex]$ 12.10$[/tex] & [tex]$\$[/tex] 1.73[tex]$ & $[/tex]\[tex]$ 689.57$[/tex] \\
\hline
\end{tabular}
About what percentage of Sonja's payments so far have gone to paying interest?