The percentage of high school seniors who graduated in four years in 2012 increased at some Douglas County schools but dropped at others as educators work toward lofty state goals. On-time graduation rates were calculated by tracking how many students who were freshmen in the 2008-09 school year graduated with a regular high school diploma last year. Statewide, the four-year graduation rate for 2012 was 68 percent, a modest gain from 67 percent in 2011, according to a recent report by the Oregon Department of Education. The other one-third of the students may graduate this year, are working on alternative …