Employees are arriving to work on time in greater numbers than in years past, according to a new survey by Chicago-based CareerBuilder that polled about 2,500 U.S. employers and nearly 4,000 workers. Last year 15 percent of workers acknowledged arriving late to work once or more each week, down from 20 percent two years ago, the study said. Why were they late? Bad weather accounted for 9 percent of excuses, while 8 percent said their tardiness was related to taking children to school. Of the employers surveyed, one-third said late arrivals led to employee firings.