An easy way to create a year counter row for a monthly$-$based model is to:

$1.$ Using ROUNDDOWN, Round the elapsed month #$/12$ down to a whole integer

$2.$ Using ROUNDUP, round the elapsed month #$/12$ up to a whole integer

$3.$ Using ROUNDDOWN, just round the elapsed month # down to a whole integer

$4.$ Using ROUND, round the elapsed month #$/12$ to a whole integer