Quarterly seasonal demand data for $3$ years is shown below. Using the seasonal forecasting methodology, solve questions $32-35$ below.

Quarters

Demand

Year $1$

$600$

$1550$

$1500$

$1500$

Year $2$

$2400$

$3100$

$2600$

IV

$2900$

Year $3$

$3800$

$4500$

III

$4000$

IV

$4900$

What is the slope of the trend equation for the annual demand in the above data?