The Figure is a line chart showing trends in vaccination coverage in Australia from 1997 to June 2015. The percentage of fully vaccinated coverage by 12 months of age was 74.9% at 31 March 1997, rising to 84.3% by 30 June 1998. Apart from a drop to 89.6% in March 2011, coverage had remained between 90% and 92% up to 31 March 2015. As at 30 June 2015, the percentage of fully vaccinated coverage by 12 months of age has increased to 93.0%. The percentage of fully vaccinated coverage by 24 months of age was 63.8% at 31 March 1998, rising to 81.7% by 31 March 2000. From 30 June 2004, coverage by 24 months remained at or near 92%, until 30 September 2014 where it decreased to 87.3%. This was likely due to the change in the immunisation coverage assessment algorithm for the 24 month milestone age which was amended to include meningococcal dose 1 and varicella dose 1 in the assessment of “fully immunised”. The 24 month assessment algorithm has been amended to look for MMR dose 2 instead of MMR dose 1. As at 31 March 2015, coverage by 24 months had increased to 89.0% and has increased again to 90.4% as at 30 June 2015. The percentage of fully vaccinated coverage by 72 months of age was 80.6% at 31 March 2002. Coverage increased steadily over 2002-2006 to 82.7% as at 31 March 2006. Over the June and September quarters of 2006 it increased sharply to 88% and then 88.8% at 30 September 2007. From September 2007, the assessment at 72 months of age was changed to assessment at 60 months of age. The percentage of fully vaccinated coverage by 60 months of age was 79% at 31 December 2007 rising to 89.6% by 31 March 2010. Coverage has increased steadily since and as at 30 June 2015 is 92.6%.