"And then," Vector continues, "the student population steadily decreases, and it's hard to get a statistically significant average percent because there was still about one Muggleborn per year, until eighty-five, that's about six years after the war ended. The total population of wizardborn stayed at about the same rate but there was a really abrupt jump in Muggleborn population, which brought up the percentage really sharply, close to about fifty percent - that's six years ago and you'll notice that well over half of our upper-year students, except the Slytherins, are Muggleborn."