Excel: IF statement with Dates

I am trying to have excel look at a cell(M2), identify which year is in the date and then fill my current cell(N2) with that year. Here is my current code below, which doesn't work.

=if(M2 = Year(2017),"2017",if(M2 = Year(2018),"2018",if(M2 = Year(2019),"2019", "Before 2017")))