After the Second World War, private religious schools had to cope with increasing rolls due to changes in the compulsory school starting and leaving ages (the school leaving age was increased to 15 in 1944; the school starting age was lowered to 6 in 1964) and the post-war baby boom. In addition, private schools had to keep pace with the drive for higher-quality facilities and smaller class sizes in the state sector, while dealing with a teacher shortage and the increasing cost of land, equipment and salaries. The Catholic school system, in particular, had to hire more lay teachers to cope with student numbers – the proportion of lay teachers in the Catholic system increased from 5 percent in 1956 to 38 percent in 1972 – and more lay teachers meant higher salary costs.