Data
The history of the borrowing policies of the European Communities is under-studied. For my PhD research, I have created dabase on the borrowing operations of the European Communities. Using the Financial Reports of the European Communities, I reported the core information of borrowing operations: amounts, maturity, interest rates, currency.
Data are available here
You can also find some descriptive statistics in the sub-sections of the research page (the ECSC, the EEC).