{
\def\sym#1{\ifmmode^{#1}\else\(^{#1}\)\fi}
\begin{tabular}{l*{4}{c}}
\hline
                    &      Wave 1         &      Wave 2         &      Wave 3         &       Overall         \\
\hline
Female              &        0.66         &        0.61         &        0.57         &        0.61         \\
                    &      (0.47)         &      (0.49)         &      (0.50)         &      (0.49)         \\
[1em]
Age$^a$             &       30.93         &       34.55         &       34.38         &       33.51         \\
                    &     (12.61)         &     (15.29)         &     (15.70)         &     (14.82)         \\
[1em]
Student, full-time  &        0.64         &        0.54         &        0.55         &        0.57         \\
                    &      (0.48)         &      (0.50)         &      (0.50)         &      (0.50)         \\
[1em]
Working, full- or part-time&        0.50         &        0.60         &        0.59         &        0.57         \\
                    &      (0.50)         &      (0.49)         &      (0.49)         &      (0.50)         \\
[1em]
Married             &        0.25         &        0.28         &        0.27         &        0.27         \\
                    &      (0.44)         &      (0.45)         &      (0.45)         &      (0.44)         \\
[1em]
Advanced degree$^b$ &        0.41         &        0.48         &        0.47         &        0.46         \\
                    &      (0.49)         &      (0.50)         &      (0.50)         &      (0.50)         \\
[1em]
Household income$^a$&      45,804         &      58,502         &      58,527         &      55,139         \\
                    &    (40,574)         &    (48,248)         &    (49,722)         &    (47,121)         \\
[1em]
Visits in the past 4 weeks, recorded&        7.04         &        7.63         &        5.89         &        6.91         \\
                    &      (5.86)         &      (6.12)         &      (5.36)         &      (5.86)         \\
\hline
\addlinespace
N & 340 & 509 & 399 & 1,248 \\
\hline\hline
\end{tabular}
}
