You are given the following information regarding sales and inventory levels over time for your firm: Year Sales Inventory 2015 $22,375 $7,200 2016 $22,929 $7,400 2017 $24,164 $7,600 2018 $24,642 $7,800 2019 $26,050 $8,000 2020 $27,083 $8,200 2021 $27,585 $8,400 2022 $28,775 $8,600 2023 $29,714 $8,800 Given this information, determine the level of safety stocks that the firm held for the five years starting in 2018 and ending in 2022.