Incidence studies were conducted in many countries across the world: thus 98 studies in Languages Other Than English (LOTE) – after translation 10 were included in the study.

The systematic review identified 100 core studies. Out of 100 core studies, 39 studies report rates only for persons, 16 report rates only for males and females, and 45 studies report rates for persons, males, and females.

The studies provided between one to 96 rates per study.

Some studies overlap in terms of different types of groups so the numbers may not add up