\documentclass{article}
\usepackage{graphicx}
\title{Spread vs Median vs FSS Trade-offs}
\begin{document}
\maketitle


In the following results, the number of selected features is rounded to the nearest 20. Note that, in all results, around 40 features (rounded) selects for the lowest PFs in all years.

\newpage
\section*{Year 1 Retention}

\includegraphics{ret1_pd.pdf}  
\includegraphics{ret1_pf.pdf} 

\section*{Year 2 Retention}

\includegraphics{ret2_pd.pdf}  
\includegraphics{ret2_pf.pdf}  

\section*{Year 3 Retention}

\includegraphics{ret3_pd.pdf}  
\includegraphics{ret3_pf.pdf}  
\end{document}