calculate the financial effect of tax havens in general due to the obfuscation of financial data. Most estimates have wide ranges (see financial effect of tax havens). By focusing on "headline" vs. "effective" corporate tax rates, researchers have been able to more accurately estimate the annual financial tax losses (or "profits shifted"), due to corporate tax havens specifically. This is not easy, however. As discussed above, havens are sensitive to discussions on "effective" corporate tax rates and obfuscate data that does not show the "headline" tax rate mirroring the "effective" tax rate. Two academic groups have estimated the "effective" tax rates of corporate tax havens using very different approaches: They are summarised in the following table (BVI and the Caymans counted as one), as listed in Zucman's analysis (from Appendix, table 2). Zucman used this analysis to estimate that the annual financial impact of corporate tax havens was $250 billion in 2015. This is beyond the upper limit of the OECD's 2017 range of $100–200 billion per annum for base erosion and profit shifting activities. These are the most credible and widely quoted sources of the financial impact of corporate tax havens. The World Bank, in its 2019 World Development Report on the future of work suggests that tax avoidance by large corporations limits the ability of governments to make vital human capital investments. Conduits and Sinks Modern corporate tax havens like Ireland, the United Kingdom and the Netherlands have become more popular for U.S. corporate tax inversions than leading traditional tax havens, even Bermuda. However, corporate tax havens still retain close connections with traditional tax havens as there are instances where a corporation cannot "retain" the untaxed funds in the corporate tax haven, and will instead use the corporate tax haven like a "conduit", to route the funds to more explicitly zero-tax, and more secretive traditional tax havens. Google does this with the Netherlands to route EU funds untaxed to Bermuda (i.e. dutch sandwich to avoid EU withholding taxes), and Russian banks do this with Ireland to avoid international sanctions and access capital markets (i.e. Irish Section 110 SPVs). A study published in Nature in 2017 (see Conduit and Sink OFCs), highlighted an emerging gap between corporation tax haven specialists (called Conduit OFCs), and more traditional tax havens (called Sink OFCs). It also highlighted that each Conduit OFC was highly connected to specific Sink . For example, Conduit OFC