Capital Allowances for Intangible Assets and the Section 110 SPV), to achieve an effective Irish CT rate, or ETR, of 0–2.5%. While low CT rates (and even lower effective tax rates), are a central part of Irish tax policy, non–CT Taxation in the Republic of Ireland is closer to EU–28 and OECD averages. Ireland's policy is summarised by the OECD's Hierarchy of Taxes pyramid (reproduced in the Department of Finance Tax Strategy Group's 2011 corporate tax policy document). As shown in , annual Irish CT has been between 10 and 16 percent of annual Total Irish Tax from circa 1994 to 2018. From 2000 to 2014, Ireland's Total Tax-to-GDP ratio was circa 27–30%, versus the OECD average of 33%. However, since Apple's Irish restructuring artificially inflated Ireland's GDP by 34.3% in 2015, Ireland's Tax-to-GDP ratio had fallen to the bottom of the OECD range at under 23%. In June 2018, tax academics estimated that Ireland was the largest global tax haven, exceeding the combined flows of the entire Caribbean tax haven system. Tax academics have also showed that being a corporate tax haven has been a prosperous economy strategy for Ireland, and most other havens. However, research also showed that the artificial distortion of Ireland's economic data, and GDP in particular, by BEPS flows, led to a large credit bubble during 2003–2007 (due to the mispricing of Ireland's credit by international markets), and an eventual credit–property–banking crisis in 2008–2013 (when Ireland's credit was re-priced). Ireland's main foreign multinationals are from periods when their home jurisdiction had a "worldwide tax" system (see Table 1), and since the UK switched to a "territorial tax" system in 2009–12, Ireland has been almost exclusively a U.S. corporate–tax haven (see Table 1). In October 2014, The Guardian quoted Bono, the lead singer of Ireland's U2, as saying that "his country's tax policies have "brought our country the only prosperity we've known"". In April 2016, award-winning Irish writer, Fintan O'Toole labelled Ireland's focus on being a U.S. corporate tax haven as the core economic model, as Ireland's OBI, (or "One Big Idea"). Multinational economy U.S.–controlled multinationals, either legally based in the U.S. or legally based in Ireland (e.g. tax inversions), dominate Ireland's economy. In June 2018, the American Chamber of Commerce (Ireland) estimated the value of U.S. investment in Ireland was €334 billion, which compared to 2017 Irish GNI* of €181.2 billion. In January 2018, Eurostat