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 $100\mathrm{.}0\%100\mathrm{.}0\%100\mathrm{.}0\%108\mathrm{.}8\%107\mathrm{.}1\%100\mathrm{.}0\%$

Cost of goods sold $75\mathrm{.}271\mathrm{.}868\mathrm{.}3117\mathrm{.}0112\mathrm{.}2100\mathrm{.}0$

Expenses $13\mathrm{.}510\mathrm{.}913\mathrm{.}0110\mathrm{.}7104\mathrm{.}5100\mathrm{.}0$

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.