\begin{table}[htb!]
\centering
\caption{Rates (\emph{m}) of detection of new molecules per year, sorted by number of atoms per molecule derived from linear fits to the data shown in Figure~\ref{cumulative_by_atoms} as well as the $R^2$ values of the fits. The start year was chosen by the visual onset of a steady detection rate, and is given for each fit. Rates and $R^2$ values are obtained from least-squares linear fits using NumPy.}
\begin{tabular*}{\columnwidth}{c @{\extracolsep{\fill}} c @{\extracolsep{\fill}} c @{\extracolsep{\fill}} c }
\hline\hline
\# Atoms    &   \emph{m} (yr$^{-1}$)    &   $R^2$       &   Onset Year      \\
\hline
2	&	0.70	&	0.98	&	1968\\
3	&	0.79	&	0.99	&	1968\\
4	&	0.58	&	0.96	&	1968\\
5	&	0.58	&	0.89	&	1971\\
6	&	0.50	&	0.88	&	1970\\
7	&	0.27	&	0.69	&	1973\\
8	&	0.40	&	0.85	&	1975\\
9	&	0.25	&	0.82	&	1974\\
10	&	0.50	&	0.76	&	2001\\
11	&	0.40	&	0.85	&	2004\\
12	&	0.34	&	0.82	&	2001\\
13+	&	0.93	&	0.90	&	2018\\
PAHs	&	1.66	&	0.87	&	2021\\
Fullerenes	&	0.05	&	0.44	&	2010\\
\hline
\end{tabular*}
\label{rates_by_atoms_table}
\end{table}\endinput