I am informed by the Revenue Commissioners that a wide range of statistical information is available on their new, enhanced, statistics webpage at www.revenue.ie/en/about/statistics/index.html. There is a section of that page dedicated to Income Tax and Corporation Tax data at www.revenue.ie/en/about/statistics/index.html#section4 in which information on the cost of credits, allowances and reliefs for the years 2004 to 2012 (the most recent figures available) can be found, under the heading "Cost of Credits, Allowances and Reliefs". This shows the cost of the claims for tax relief on health expenses, which includes medical and dental expenses.