Apartment vacancies in metro Denver have dropped to their lowest level since 2001---an average of 6.1 percent. The reason for the shrinking number of vacant apartments is twofold: More people are moving to Colorado at a time when fewer apartments are being built, and many of them are finding roommates to save money, reports The Denver Post. The shift is dramatic. The vacancy rate was lower only in two other quarters over the past nine years: 5.3 percent in the third quarter of 2007 and 5.9 percent in the first quarter of 2008. And in the fourth quarter of 2007, it was also 6.1 percent. Moreover, "there's just nothing [to be built] in the pipeline," according to Gordon Von Stroh, a professor of business at the University of Denver who authored a report revealing the stats. The numbers aren't likely to change anytime soon without more apartment development, and roughly 180,000 young adults will turn 20 in the next five years. For now, the metro-wide average rent has gone up, year over year, from $870 to $899 during the second quarter. "We're starting to see signs of more significant increases in rents," Ryan McMaken, a spokesman for the state Division of Housing, tells INDenverTimes. The issue isn't unique to Denver. In Boulder and Broomfield counties, for instance, the second-quarter vacancy rate was even tighter: 4.9 percent, according to the Daily Camera.