The following is the July 4, 2016 report, Defence Expenditures of NATO Countries.
From the report:
NATO collects defence expenditures from Allies on a regular basis and presents aggregates
and subsets of this information. Each Allied country’s Ministry of Defence reports current
and estimated future defence expenditure according to an agreed definition of defence
expenditure, and represent payments actually made, or to be made, during the course of
the fiscal year. NATO also makes use of up-to-date economic and demographic information
available from the Directorate-General for Economic and Financial Affairs of the European
Commission, and the Organisation for Economic Co-operation and Development. In view
of the differences between this definition and national definitions, the figures shown may
diverge considerably from those which are quoted by national authorities or given in national
budgets. Research and development expenditures related to major equipment are included
in equipment expenditures and pensions paid to retirees in personnel expenditures.