text: The age and year of birth distributions are also similar and are shown in the Appendix. Thus, for 
  the majority of the analysis that follows, tests with no PNC number were excluded.10 
  
  The charts and tables above use data from all positive tests, so will include cases where the 
  same individual has tested positively on more than one occasion. The following data look just at 
  the first test for each individual testing positive for opiates-only or positive-for-both. 