Solve for the unknown number of years in each of the following: $($Do not round intermediate calculations and round your answers to $2$ decimal places, e$.$g$.,32\mathrm{.}16.)$

$\backslash$table$[[$Present Value,Years,Interest,Rate,Future Value$],[$$$,530,,,\%,1,166],[,780,,12,\%,1,975],[,18,100,,18,\%,314,892],[,21,200,,14,\%,338,250]]$