If you thought you shouldn't be alarmed by serial killers approaching the society in greater numbers claiming more victims year and year after then read these key points -
The USA has more than three quarters of all serial killers and it only has 6% of the world's population.
I have read statistics that 35 or maybe even 100 serial killers are active in the USA at one time.
They may be responsible for one to two thirds of the annual homicide rate.
Between 1906 and 1959, each year would produce on average 1.7 new cases of serial killers. Through the 1960's the figure grew to 5 a year, and by 1980 it had tripled. By 1990, it was 36 per year - which averages out to three a month, and represents a rise of 940% in the space of three decades.
The FBI have estimated that, by the millennium, serial murders could be claiming an average of eleven lives a day.
Rest of The World
Not only is the USA a place for serial killers but other countries are experiencing the great impact to their societies by the serial murder phenomenom. So much so that their police have little to none experience attempting to solve a serial killer case.
Lack of police experience(because their country has probably never had a serial killer before) allows a killer to go about even more rampantly(this is more so the case in non-western world countries) claiming more victims in a lesser time span compared to the US serial killers; non-US countries are also aware of a serial killer far more earlier in their murders most of the time where some US serial killers(particularly the stable killers) can go about without even the society knowing of their existence(this is attributed to missing persons).
Evidence that non-US serial killers claim more victims than the American ones is evident - Pedro Lopez, the 'Monster of the Andes' killed 300+ women in South America in the early 1980's; Andrei Chikatilo 'Citizen X' killed 53+ people in Russia from 1980 to 1990(the detectives of the case considered serial killers to be a American phenomenon and did not ask the FBI for help). US serial killers do not claim these huge figures but there are more of them so the total numbers of people murdered in the USA is greatly higher.
Countries such as the UK, Australia and South Africa etc. are experiencing the serial killer problem which has appeared in the last 50 years. The UK has had its fare share of serial killers - Jack the Ripper(considered the first serial killer), John George Haigh, John Christie, Ian Brady & Myra Hindley, Peter Sutcliffe, Dennis Nilsen, Michael Lupo, Colin Ireland etc. Australia - John Wayne Glover, Ivan Milat, etc. South Africa - Norman Simons, Moses Sithole etc. These countries have also attempted to fight it in a big way establishing behavioral units in their countries and affiliating information with the FBI's Behavioral Science Unit.