Suppose that AlwaysRain Irrigation's marketing department will undertake an intense ad campaign for the bronze sprinklers, which are more expensive but also more durable than the plastic ones. Forecast demand for th enext four years is

Year $1$ demand $($in $000$s$)$

Year $2$ demand $($in $000$s$)$

Year $3$ demand $($in $000$s$)$

Year $4$ demand $($in $000$s$)$

Plastic $90$

$32$

$44$

$55$

$56$

Plastic $180$

$15$

$16$

$17$

$18$

Plastic $360$

$50$

$55$

$64$

$67$

Bronze $90$

$11$

$15$

$18$

$23$

Bronze $180$

$6$

$5$

$6$

$9$

Bronze $360$

$15$

$16$

$17$

$20$

For this new set of demands, how many bronze machines are needed in year $4?$