Hot Spot is a firm based in the United States whose core business is the maintenance of home heaters. The company usually forecasts service requests based on the number of installed heaters. The number of installed home heaters and the number of service requests received over past years in New Jersey are reported:

Year Services requests

$18,672$

$19,076$

$20,994$

$23,24925,025$

$28,111$

$30,985$

$33,397$

Develop the four forecasting models.

Determine which the best model to project year $9$ is$.$