\begin{table}[htbp]\centering
\caption{Robust IV Estimates of Log Registrations per Capita on Log Highway Gas Use per Capita \label{tab:GasUsePerCapitaiv}}
\begin{tabular}{l*{4}{c}}
\hline \hline \multicolumn{5}{l}{\textit{Panel A: IV Estimates and Robust 95\% Confidence Intervals}} \\&            &            &            &            \\
\multicolumn{5}{c}{Dep. Var.: Log Number of Vehicle Registrations} \\ &         (1)&         (2)&         (3)&         (4)\\
$\gamma$    &      -0.737&       -0.82&       -0.79&       -1.31\\
95\% Conf. Set&\makecell{(-$\infty$, $0.11]$; \nextline $[19.76$, $\infty$)}&\makecell{(-$\infty$, $0.14]$; \nextline $[19.77$, $\infty$)}&[-5.72, 0.07]&\makecell{(-$\infty$, $0.12]$; \nextline $[2.28$, $\infty$)}\\
\makecell[l]{Data Source \nextline Controls}&        None&  Documented&\makecell{Large \nextline Undocumented}&\makecell{Small \nextline Undocumented}\\
State Fixed Effects&           Y&           Y&           Y&           Y\\
Year Fixed Effects&           Y&           Y&           Y&           Y\\
\makecell[l]{State-Specific Linear \\ Time Trends}&           Y&           Y&           Y&           Y\\
Common Controls&           Y&           Y&           Y&           Y\\
Number of Obs.&       2,429&       2,429&       2,429&       2,429\\
\hline \hline \multicolumn{5}{l}{\textit{Panel B: Anderson-Robin Test Statistics and P-Values}} \\&            &            &            &            \\
 \multicolumn{5}{c}{\underline{$ H_{0}:\gamma=11$}} \\ AR Stat&     4.005**&     4.009**&     5.271**&       1.815\\
p-value     &       0.045&       0.045&       0.022&       0.178\\
            &            &            &            &            \\
 \multicolumn{5}{c}{\underline{$ H_{0}:\gamma=9.7$}} \\ AR Stat&     4.053**&     4.058**&     5.323**&       1.877\\
p-value     &       0.044&       0.044&       0.021&       0.171\\
            &            &            &            &            \\
\multicolumn{5}{c}{\underline{$ H_{0}:\gamma=$1}} \\ AR Stat&     5.707**&     5.489**&     6.430**&     6.170**\\
p-value     &       0.017&       0.019&       0.011&       0.013\\
            &            &            &            &            \\
\multicolumn{5}{c}{\underline{$ H_{0}:\gamma=$-4.8}} \\ AR Stat&       2.685&       2.612&      3.633*&       0.631\\
p-value     &       0.101&       0.106&       0.057&       0.427\\
            &            &            &            &            \\
\multicolumn{5}{c}{\underline{$ H_{0}:\gamma=$-6.1}} \\ AR Stat&      2.890*&      2.833*&     3.908**&       0.761\\
p-value     &       0.089&       0.092&       0.048&       0.383\\
\hline \hline \end{tabular} \vspace{0.2cm} \begin{tablenotes} \begin{spacing}{0} \begin{footnotesize} \item \textbf{Notes:} The top panel of this table presents IV estimates and 95\% confidence sets robust to weak instruments of the linear relationship between log highway gas use per capita and log vehicle registrations per capita.  The bottom panel presents Anderson-Rubin chi-squared statistics along with p-values for different null hypotheses pertaining to the parameter estimated in the top panel.  The unit of observation is state-year.  The four specifications pertaining to different levels of  (DSCs) and control specifications are documented in Table \cref{ssec:Spec}. Confidence sets are based on standard errors clustered by state. * p\textless 0.1, ** p\textless 0.05, *** p\textless 0.01 \end{footnotesize} \end{spacing} \end{tablenotes} \end{table}
