incidence
US /ˈɪn.sɪ.dəns/
UK /ˈɪn.sɪ.dəns/

1.
the occurrence, rate, or frequency of a disease, crime, or other undesirable thing
:
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The incidence of measles has decreased significantly due to vaccination.
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There was a high incidence of crime in the area last year.
2.
the way in which something happens or arises
:
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The incidence of light on the surface affects its color.
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We need to study the incidence of various factors on the outcome.