text: 18 Data for 2014 was available until October 2014. This was converted to annual figures by multiplying up by 1.2 to account for 
  the missing months in a linear fashion. 
  
  19 The percentages from this table can be calculated from the numbers in Table 13. 
  20 In reality there is always a trade-off in this methodology between the up-to-dateness of the cohort used to measure the lag- 
  to-treatment and the number of years of lag measured, i.e. we could use a more recent cohort, say 2008. But that would 
  mean excluding all those who take longer than seven years to come to treatment, an even larger proportion. We are 
  indebted to Tim Millar for providing the dataset used to model the ‘tail’ of the distribution. It contained a longer time series of 
  
  New opiate and crack-cocaine users: characteristics and trends  23 