"Les dernières années"
Why is the word ''year'' sometimes année (f.) and sometimes an (m.)?
When the word is written along a descriptive expression (in this case, dernière) you use the feminine (words alike too, e.g. journée), although there are exceptions. Look: http://french.about.com/od/vocabulary/a/an-annee-jour-journee-matin-matinee-soir-soiree.htm