Median year-over-year pay change for people employed at the same institution in two consecutive fiscal years — the raise an existing employee actually saw, unclouded by new hires and departures.
Each point is the median of (this year’s total salary − last year’s) ÷ last year’s, over people present both years with salary > $1,000. A promotion or a move to full-time shows as a large raise; the median damps those. FY2016 is the first year a raise can be computed (needs FY2015 as the prior year).