The results show that in 2016 there were 30 attacks that resulted in fatalities and 23 in 2015, compared to just two in 2014 and five in 2013.
The increase means 26.5 people on average were killed in each attack in 2015 and 2016 – a shocking spike from the average of four in the previous three years.
ISIS has claimed responsibility for seven of the 10 deadliest attacks since 2012.
Dr Sajjan Gohel, International Security Director with the Asia-Pacific Foundation think tank, said: “It’s very different to the al Qaeda threat, which was obsessed with mass casualties, bringing down airliners.
“What ISIS is trying to do is have a greater volume of attacks, but make it more cost effective and simpler.”
Despite the change in tactics, firearms remain the primary weapon used by terrorists.
The single deadliest attack to be recorded in Western Europe was in Paris when 130 people died in November 2015.
The nightmarish day of terror started with a bombing outside the Stade de France stadium, which was the first of three explosions.
The terrorists then launched co-ordinated gun attacks at popular nightlife spots such as bars and restaurants in Paris.
Three gunmen also opened fire at Bataclan concert hall and murdered spectators watching rock band Eagles of Death Metal.
Last year, a terrorist in a lorry drove through crowds of revellers in Nice, France on Bastille Day killing 84.
In June, three terrorists went on the rampage with knives at Borough Market in London before being shot dead by police.
Weeks earlier, Salman Ramadan Abedi detonated a shrapnel-laden bomb at the exit of Manchester Arena, following a concert by American singer Ariana Grande killing 22.