The number of men and women in the US aged 60 or over still in work 1) (RISE) for more than a decade. Economists 2) (GIVE) a number of reasons for this trend. First, since 1985 the US economy 3) (EXPAND) so there 4) (BE) an increased demand for labour. At the same time, the cost of some services, such as health care, 5) (INCREASE) so workers need to earn more money in later life. In addition, changes in social security benefits and rules 6) (HAVE) a considerable effect on labour patterns. First, in 1977 and 1983 changes to the Social Security Act 7) (RAISE) the full-benefit age from 65 to 67 and 8) (INTRODUCE) other changes that make delaying retirement more attractive. Then, in 1986 the Age Discrimination Act 9) (END) compulsory retirement for all workers, allowing them to work later in life. Changes to pension laws 10) (ALSO ENCOURAGE) workers to stay in employment longer, as this gives them more chance of a larger pension when they retire.