Family Home & Security Incorporated sells padlocks. It reported an increase in net sales from $$4\mathrm{.}2$ billion in $2017$ to $$4\mathrm{.}5$ billion in $2018,$ and an increase in gross profit from $$1\mathrm{.}2$ billion in $2017$ to $$1\mathrm{.}4$ billion in $2018.$

Calculate each year$$s gross profit percentage. $($Round your answers to $1$ decimal place.$)$

The change in gross profit represents: