Common$-$size and trend percentages for a company$$s net sales, cost of goods sold, and expenses follow:

Common$-$Size Percentages Trend Percentages

$202320222021202320222021$

Net sales $100\mathrm{.}0\%100\mathrm{.}0\%100\mathrm{.}0\%108\mathrm{.}2\%106\mathrm{.}8\%100\mathrm{.}0\%$

Cost of goods sold $68\mathrm{.}565\mathrm{.}362\mathrm{.}5114\mathrm{.}4110\mathrm{.}4100\mathrm{.}0$

Expenses $21\mathrm{.}217\mathrm{.}519\mathrm{.}5112\mathrm{.}6105\mathrm{.}3100\mathrm{.}0$

Required:

a$.$ Calculate the profit percentage for $2021,2022$ and $2023.($Round the final answers to $2$ decimal places.$)$

b$.$ Determine whether the company$$s profit increased, decreased, or remained unchanged during this three$-$year period.