evidence: Revenue is projected to rise in 2018–19 by at least 1 percent of GDP in 13 countries (e.g., Burkina Faso, Sierra Leone, Uzbekistan), but fall relative to GDP in 13 countries (e.g., Malawi, Lao P.D.R., Tajikistan). [...] Revenues declined in 2018–19 by at least 0.5 percent of GDP in 12 countries (e.g., Ethiopia, Tanzania, Vietnam) while increasing by at least this margin in 10 others (e.g., Cambodia, Niger, Nepal). [...] Okello and others (2019) elaborate on this.