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\begin{tabular}{c c c c c}
     \toprule
     \multirow{3}{*}{\bond{Characteristic}} & \multicolumn{2}{c}{\textbf{12-17 years of age}} & \multicolumn{2}{c}{\textbf{18-25 years of age}}\\ \cline{2-5}
     &Intermittent^a & Daily^b & Intermittent^a &  Daily^b\\
     & \% (95\% CI) & \% (95\% CI) & \% (95\% CI) &  \% (95\% CI)\\
     \toprule

\end{tabular}
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