In March 2005, the House of Commons Public Accounts Committee, charged with ensuring value for money in public spending, published a report concluding that it was "impossible to determine" whether the PPP was better value than a publicly run investment programme, primarily because of the untested periodic review structure of the 30-year contracts. These were to be revised every 7.5 years, meaning that the ultimate price for the promised £15.7 billion of investment was still unknown. It noted that using public bond finance would have saved £90 million a year in financing costs, even though the Government guaranteed repayment of 95% of costs in the event of premature termination, and the contracts placed limits and exemptions on financial risk transferred to the infrastructure companies. The system still received an annual public subsidy of £1 billion, but its spending was now determined entirely by the infracos' interpretation of their 2000-page PPP contracts. Although the private operators were expected to receive at least 18–20% returns on capital (for Metronet), for the type of risk associated with major upgrades, most of the work was low-risk maintenance and replacement. The public-sector procurement option (using private companies for specific major projects) would also have saved the £455 million cost of concluding the PPP contracts, not to mention the five years' delay the contract negotiations caused.