I have this book "The Evolution of Suicide" and there it says:
Suicide is not rare. It may appear exceptional from an individual's perspective, as
might be said of death generally – suicide reportedly occurs at an annual rate of
"only" about 11.4 per 100,000 population globally (WHO, 2014) – but it is far from
an uncommon cause of mortality. No less than 1.4% of all deaths are attributed to
suicide, some 800,000 per year, which makes it the world's leading cause of violent
fatality: more people die by self-murder than by wars and homicide combined
(WHO, 2012a, 2014). The real incidence may be higher, with perhaps a fifth of
suicides going unreported in official statistics (Kapusta et al., 2011; Rockett,
Kapusta, & Bhandari, 2011): such is the stigma that often surrounds suicide that
many cases are misclassified as deaths by other or unknown causes (Tøllefsen, Hem,
& Ekeberg, 2012). Actual deaths can be viewed as the tip of an iceberg of suicidality: it is estimated that for each completed suicide, there are 20–25 "unsuccessful"
attempts (Troister, 2014) and that 2.7% of people in the world have tried to take
their own lives at some stage, 0.4% over a 12-month period alone (WHO,
2014). Reported rates of suicidal ideation very widely: an international study found
that 10–18% of the general population reported having had suicidal thoughts at
some stage (Weissman et al., 1999); towards a higher end of results, a survey of
shoppers in Seattle found that 53–67% admitted to have seriously considered suicide at some stage, 20% in the past year alone (Linehan, Goodstein, Nielsen, & Chiles, 1983).