Sandor is trying to identify a linear relationship linking the amount of heat $($x$)$ applied in the final hardening stage to the heavy duty steel bolts that his company produces for bridge construction and the strength of those bolts $($y$).$ Below is a table showing data for a sample of five of the bolts.

Temperature vs$.$ Strength Index

Heat $($oF$)$

Strength index

$2400$

$820$

$1800$

$600$

$2000$

$840$

$1200$

$620$

$2600$

$920$

What is the correlation in percent terms $($ie$,\mathrm{.}24$ must be entered as $24\mathrm{.}00)?$