It depends on the area. In Russia the missionaries get b3at up routinely. In the inner-city of the US (where I served a mission) missionaries are frequently r0bbed at gunpoint and sometimes sh0t. Unless the missionary d1es the incident is never widely reported (since this would dissuade potential future missionaries from serving). In some areas (often in the Cath0lic parts of Latin America) the gang members are superstiti0us and believe that hurting a Christian missionary or allowing other gangs to do so in your territory will incur divine wrath, so they will quietly protect the LDS missionaries when needed. In the most extr3me areas (like parts of Honduras), missionaries are told to avoid the cities entirely (except to fly home) and live in the jungle for 2 years.
Probably way way lower than the general murder rate. Either they are being protected by God, or they are being pulled out at the slightest sign of danger.
For those claiming that Mormons will only leave their missions when danger is “off the charts:” fourteen Mormon missionaries have been kîlled in the past hundreds years, out of millions of Mormon missionaries in that time period.
Only Mormon martyrs in the 20th century were mürdered by other Mormons.
Don’t fall for their propaganda.