The uncertainty arises due to the assessment: assumptions with respect to the ETI and from the long horizon of the projections. [...] The assumptions and calculations underlying the SPSD/M simulation results were prepared by the Office of the Parliamentary Budget Officer (PBO) and the responsibility for the use and interpretation of these data is entirely that of the PBO. [...] The assumptions and calculations underlying the simulation results were developed by the Parliamentary Budget Officer, who is solely responsible for the use and interpretation of the data. [...] The assumptions and calculations underlying the simulation results were prepared by PBO and the responsibility for the use and interpretation of these data is entirely that of the author.