the annual figures of returns covering the period 2011-2013 show so far a dramatic increase in IOM voluntary returns, but are rather steady when it comes to forced returns. 44 In this sense, the overall consent rate among Amygdaleza's detainees is very low. As far as irregular arrivals are concerned, the sample of Amygdaleza is too small and too recent to allow an estimate on the long-term discouraging effect of detention. The police statistics show a decrease in the number of new arrivals in Greece during the period 2011-2013.45 However, it is too early to draw conclusions on how permanent this decline is going to be and to what extent it is the direct outcome of a short-lived new policy or related to a wide range of other parameters. 46 Overall, this leaves Amygdaleza with an effectiveness rate of 27,9% in returning migrants and a rough rate of 14% with regard to consent. There are two ways to assess the cost effectiveness of this policy. One is to look at the direct costs and compare them against the forthright results, in order to evaluate if this policy is good value for money. A second way is to take into account also the indirect costs involved in the implementation of this policy, which allows a wider contextual analysis. These are often hidden and their precise amount is not always easy to calculate. a. Effectiveness v. Direct Costs Amygdaleza currently runs on a budget of €10,500,000 per year, which as analysed earlier is equivalent to a minimum of €14 per detainee per day. It has a proven success rate in returns of 27,9%. The National Action Plan foresees the creation of 10,000 by the end of 2014, which means that Greece would end up paying 14euros/day x 10,000places = 140,000 euros/day when these centers are running at full capacity. Looking now at the wider picture, according to the United Nations Special Rapporteur on Migrants, the population of irregular migrants currently residing in Greece is estimated at 470,000. 47 If we adopt this figure, under Greece's new policy of indiscriminate detention, all 470,000 migrants would have to be detained at some point, in order to filter who stays and who leaves. The cost to carry out such a plan would be 470,000 x 14 euros = 6,580,000€ per day or 46,060,000€ per week or €197,400,000 per month until all 470,000 cases have been processed. Not only is such a policy financially unsustainable under the current funds, but also unjustifiable with a 27,9% success rate in returns through detention and an average of 14% consent rate. b. Effectiveness v. indirect costs Some of the indirect costs are: 1. The additional medical costs to treat the adverse health effects of detention. It is widely accepted that detention as such — let alone under unhygienic conditions — has a negative impact on the physical and mental health of both staff and detainees. When these are transmissible, they tend to spread rapidly. The most common problems in Greek detention centers are skin diseases, respiratory 44 45 46 47 Data provided by the Greek Police Headquarters. See above Table 1. On parameters which can influence the measurable size of the irregular migrant population see for e.g. http://www.oecd.org/els/mig/GREECE.pdf . Supra fn. 11, page 5, par. 9. 9