The excluded category is workers with less than an elementary education, so that university graduates are shown as earning about 140 percent more than those workers. Again, there is some evidence of a modest decline in the return during the 1990s, but the differential between the earnings of secondary and university graduates has remained very stable. The regressions typically accounted for about 50 percent of the variation in the wage rate, with no significant difference between the linear and the categorical versions of the education measure.