The European Commission's own October 2025 evaluation of the EU Public Procurement Directives states that public authorities spend 'around 15% of GDP' on procurement — slightly above the 14% figure used by the MEP, though within normal rounding/definitional variation.
The 14% share is a long-standing estimate (the European Commission used 13.3% for 2017); the exact percentage varies by source and year (e.g. Hermix reports 13.6%, the Commission reports ~15%), reflecting different methodologies and reference years rather than a single fixed value.