The lure of home: More Americans are staying put each year. According to a Census Bureau report released last week, only 15.9 percent of the population changed addresses between March 1998 and March 1999, down from 16 percent the year before. The percentage of Americans moving has steadily decreased since 1984-1985, when 20.2 percent of the population moved. Demographer Carol Faber credited an aging population for the trend: "The older you get, the less likely you are to move." Teen sexual activity: The Centers for Disease Control last week reported that teens are a bit less likely to be sexually active now than teens were in the early 1990s. CDC surveys found that 50 percent of teens reported ever having had sex in 1999, down from 54 percent in 1991. Sixteen percent said they'd had four or more partners, down from 19 percent.