It is $2021.$ Calculate the inflation premium for a bond maturing in $21$ years given the following inflation estimates:

Expected Inflation for $2022$: $2\%$

Expected Inflation for $2023$: $2\mathrm{.}5\%$

Expected Inflation for $2024$: $2\mathrm{.}8\%$

Expected Inflation for $2025-$infinity: $3\mathrm{.}1\%$