You don't have to think the world is becoming safer, it absolutely is. And not just safer, but more prosperous and wealth is more distributed then ever. Here is just a single article going over many of these things: http://www.theatlantic.com/international/archive/2015/12/goo...
Personally, I don't find such topline metrics that helpful. If India improves by some margin (noting that it is a country with relatively more space to grow than a developed nation) then the averages for the whole World would improve, given that India represents 1/6th the global population. This would mask any relative declines in pockets/cities in a country like the US.
NB I only very quickly skimmed the article, and base this opinion on the usage of broad terminology like "the World is...". It may be objectively true but is not really pertinent to the discussion of whether Chicago is or is not getting safer...
