The manager of Champion Cooling Company has recently implemented a statistical process control method. The accompanying table shows the recorded temperatures of five different samples of walk$-$in coolers that were produced in the previous month.

$$ Sample $1$ Sample $2$ Sample $3$ Sample $4$ Sample $5$

Unit $1104\mathrm{.}0100\mathrm{.}1101\mathrm{.}1102\mathrm{.}0102\mathrm{.}7$

Unit $2106\mathrm{.}4104\mathrm{.}4100\mathrm{.}4105\mathrm{.}9105\mathrm{.}4$

Unit $3101\mathrm{.}8103\mathrm{.}6103\mathrm{.}0104\mathrm{.}6106\mathrm{.}1$

Unit $4105\mathrm{.}6101\mathrm{.}4101\mathrm{.}0102\mathrm{.}1102\mathrm{.}5$

Unit $5100\mathrm{.}6100\mathrm{.}7104\mathrm{.}9107\mathrm{.}0102\mathrm{.}0$

Use the information in Table $5\mathrm{.}4.$ The center line of the R$-$chart is: