The potential support ratio, or PSR (the number of persons aged 15-64 years per one older person aged 65 years or older), indicates the dependency burden on potential workers. The impact of demographic ageing is visible in the PSR, which has fallen and will continue to fall. Between 1950 and 2009, the PSR fell from 12 to ____ people in the working ages per each person 65 years or older, and is estimated to drop to 4% in 2050.