Question: What are is the correlation between stock Xs return and stock Ys return?

\begin{tabular}{lccc} \hline Year End & Stock X Realized Return & Stock Y Realized Return & Stock Z Realized Return \\ \hline 2004 & 20.1% & 14.6% & 0.2% \\ \hline 2005 & 72.7% & 4.3% & 3.2% \\ \hline 2006 & 25.7% & 58.1% & 27.0% \\ \hline 2007 & 56.9% & 71.1% & 27.9% \\ \hline 2008 & 6.7% & 17.3% & 5.1% \\ \hline 2009 & 17.9% & 0.9% & 11.3% \\ \hline \end{tabular}