A land title search office has a staff of three, each working eight hours per day (for a total payroll cost of $480/day) and overhead costs of $300 per day. This office processed an average of seven titles each day. The office recently purchased a computerized title-search system that will allow the processing of an average of 12 titles per day. Although the staff, work hours, and pay will be the same, the overhead costs are now $600 per day. Calculate the labour productivity in the old and the new systems. How much (in percentage) has the labour productivity grown?