Consider the following seasonal decomposition forecasting model for Expenses, which are measured quarterly. Period Sales

$11280$

$21260$

$31380$

$41350$

$51290$

$61120$

$71190$

$81230$

$91080$

$101120$

$111060$

$12940$

$13920$

$14768$

$15670$

$16650$

$17679$

$18678$

$19450$

$20200$

Step $1$ of $3$: Interpret the seasonal index for quarter $1.$