Presumption concerning trafficking
17.  Any person who is proved to have had in his or her possession more than —
(a)100 grammes of opium;
(b)3 grammes of morphine;
(c)2 grammes of diamorphine;
(d)15 grammes of cannabis;
(e)30 grammes of cannabis mixture;
(f)10 grammes of cannabis resin;
(g)3 grammes of cocaine;
(h)25 grammes of methamphetamine;
(ha)113 grammes of ketamine; or
(i)10 grammes of any or any combination of the following:
(i)N, α-dimethyl-3,4-(methylenedioxy)phenethylamine;
(ii)α-methyl-3,4-(methylenedioxy)phenethylamine;
(iii)N-ethyl-α-methyl-3,4-(methylenedioxy)phenethylamine,
whether or not contained in any substance, extract, preparation or mixture, is presumed to have had that drug in possession for the purpose of trafficking unless it is proved that his or her possession of that drug was not for that purpose.