Distribution, measures of centres and outliers. So pick each of those metrics and compare them over the years.
How has the distribution changed over the years? Did it get more variable? Or did it get less variable? Did it change at a consistent rate or did it vary, i.e. get high then low.
ANOVA, or Analysis Of Variance, is used to compare the averages or means of two or more populations to better understand how they differ. Watch this tutorial for more.