The
plague year proved brutal for Chicago, already a violent city even by American
standards. Murders increased by 56% from 2019—nearly three times as many
victims as in all of Italy. As crime data from 2020 are compiled, one thing has
become clear: American cities saw the biggest rise in homicides in decades,
currently estimated at 30% in a single year.
请问老师：该怎么理解破折号和冒号的句法作用？然后nearly three times as many victims as in all of Italy前是省略了which is吗？
