A reconciliation of the tax charge/(credit) applicable to loss before tax at the statutory rates for the countries (or jurisdictions) in which the Company and the majority of its subsidiaries are domiciled to the tax expense/(credit) at the effective tax rates is as follows: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 2022 | | | | 2021 | | | | 2020 | | | | US$’000 | | % | | US$’000 | | % | | US$’000 | | % | Loss before tax | (445,724) | | | | | (407,196) | | | | | (308,285) | | | | At the statutory blended US federal and state income tax rate of 28.1% (2021 and 2020: 28.1%) | (125,293) | | | 28.1 | | | (114,463) | | | 28.1 | | | (86,659) | | | 28.1 | | Effect of tax rate differences in other countries and regions | 15,129 | | | (3.4) | | | 15,027 | | | (3.7) | | | 35,062 | | | (11.4) | | Research and development credit | (24,970) | | | 5.6 | | | (954) | | | 0.2 | | | (15,643) | | | 5.1 | | State rate change | (107) | | | — | | | — | | | — | | | — | | | — | | Effect of non-deductible expenses | 1,829 | | | (0.4) | | | 2,298 | | | (0.6) | | | 383 | | | (0.1) | | Tax losses and deductible temporary differences not recognized | 131,194 | | | (29.4) | | | 102,481 | | | (25.2) | | | 26,040 | | | (8.4) | | Option income tax benefit | 2,668 | | | (0.6) | | | (9,532) | | | 2.3 | | | (442) | | | 0.1 | | Prior year true up | — | | | — | | | — | | | — | | | — | | | — | | Uncertain tax positions | — | | | — | | | — | | | — | | | — | | | — | | Withholding tax on interest | — | | | — | | | — | | | — | | | — | | | — | | Others | 175 | | | — | | | 1,529 | | | (0.4) | | | (653) | | | 0.2 | | Tax charge/(benefit) at the Company’s effective rate | 625 | | | (0.1) | | | (3,614) | | | 0.9 | | | (41,912) | | | 13.6 | |
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