Since their introduction in the 1998 comprehensive spending review (CSR), public service agreements (PSAs) have played a vital role in galvanising public service delivery and driving major improvements in outcomes. Department's performance in the previous spending review period is always taken into consideration in any new spending review. The Prime Minister's delivery unit was established in 2001, and while delivery of PSAs is ultimately the responsibility of individual Departments PMDU and HM Treasury work closely to support Departments to ensure delivery against these challenging commitments. Currently 70 per cent. of SR02 PSAs are assessed as met, met-ongoing or partly met, while 56 per cent. of SR04 PSAs are assessed as met, ahead or on course.