The ratio of senior citizens in South Korea increased nearly 4 percent over the past decade, data showed Thursday, indicating that the country's population is aging at a fast pace. According to the data by Statistics Korea, the ratio of those aged 65 or older accounted for 10.9 percent of the country's total population in 2010. It is higher than 7 percent in 2000 and 8.9 percent in 2005.