Fig. 4

Model system Eqs. (2)–(5) fitted to data for individuals under outpatient rehabilitation in Cape Town. The blue circles indicate the actual data and the solid red line indicates the model fit to the data. The percentages are not of all users, but of those in rehabilitation. Starting from the second half (July–December) of the year 2008 up to the first half (January–June) of the year 2013, the majority of patients in specialist treatment centres of Cape Town were now being treated on an outpatient basis. It shows a good fit to the data from Table 1