In 2014, the Africa oil producing country was ranked fourth.
Going by the latest ranking, Nigeria is only better than two Middle Eastern countries – Iraq and Afghanistan – who were ranked first and second respectively.
Another two Middle East countries, Pakistan and Syria are ranked fourth and fifth respectively, after Nigeria.
The only African countries closer in ranking to Nigeria are Somalia and Libya which are in the eighth and ninth positions respectively.
France, which recently experienced deadly terrorist attacks that killed about 160 people in Paris, is ranked 36th, same as the United States of America.
"Terrorist attacks are much more lethal in Nigeria than any other country," the GTI report said.
The report, released on November 16, 2015 by the Institute for Economics and Peace, said the Islamist terror group in Nigeria, Boko Haram, overtook ISIL in 2014 to become the most deadly terrorist group in the world.
The Institute for Economics and Peace is an independent, non-partisan, non-profit think tank with offices in Sydney, New York and Mexico City.
The 2015 GTI report said Boko Haram, in 2014, was also able to spread outside Nigeria to launch two deadly attacks in neighbouring Cameroon, killing 530 people.
Cameroon, the report said, didn’t record any death from terrorism between 2000 and 2013 until Boko Haram struck in 2014.
Although published in November 2015, the GTI report was produced from data gathered in 2014.
In 2014, Nigeria experienced the biggest yearly deterioration in terrorism on record, the report said.
"There were 5,662 more people killed (in Nigeria) from terrorism in 2014 than in 2013, an increase of almost 300 per cent," it says.
The number of people killed in Nigeria by terrorist attack in 2014 was 6,118, compared to the 1,595 killed in 2013.
According to the report, "Nigeria has moved from the country with the fifth highest levels of fatalities in 2013 to the second highest in 2014."
In summary, Nigeria recorded 662 terrorist attacks in 2014, with 7,512 people killed, 2,246 injured and 1,512 properties destroyed.
But then, Boko Haram isn’t the only terror group in Nigeria that kills; the Fulani militants in the northern part of Nigeria is recorded to have killed as many as 1,229 people in the country in 2014, which is an incredible leap from 63 recorded in 2013.
Unlike religious fanaticism which drives Boko Haram, the Fulani militants are driven by conflict over access and control of land between the semi-nomadic Fulani herdsmen and farmers in north-eastern Nigeria, the report said.
Nigeria, alongside four other countries – Iraq, Afghanistan, Pakistan and Syria – accounted for 78 per cent of lives lost globally in 2014 through terrorist attacks. Of 20 most fatal terrorist attacks in the world in 2014, nine of them took place in Nigeria.
Boko Haram was responsible for eight of those nine attacks, while the Fulani militants were responsible for one which took place at Galadima where 200 people were reportedly killed.
The worst terrorist attack in Nigeria in 2014, according to the 2015 GTI report, was in Kano city on November 28, 2014 when two suicide bombers and roadside bomb detonated at the Grand Mosque in the city.
Boko Haram terrorists reportedly opened fire on worshippers fleeing the explosions. One hundred and twenty-two (122) people were killed, while 270 were injured.
Nigeria for several years now has been battling Boko Haram insurgency which is responsible for thousands of deaths in the northeast of the country.
"The nature of terrorism in Nigeria is different to Iraq and Afghanistan," the report said.
"Terrorist activity in Nigeria has more in common with the tactics of organised crime and gangs, focusing more on armed assaults using firearms and knives than on the bombings of other large terrorist groups."
"Firearms were used in over half of all attacks in Nigeria and were responsible for 67 per cent of all deaths by Boko Haram and 92 per cent of deaths from Fulani militants."
Whilst previously the use of suicide attacks by Boko Haram was rare, in 2014 they were responsible for 31 suicide attacks with an average of nearly 15 deaths per attack.
"The majority of these attacks were against private citizens and education and religious institutions. No other group in Nigeria conducted suicide attacks in 2014," the report said.
The number of people killed by terrorism around the world increased from 18,111 in 2013 to 32,658 in 2014.
The increase is said to be the largest ever recorded.
The report put the global cost of terrorism in 2014 at US$52.9 billion, compared to US$32.9 billion in 2013.
The GTI, which is currently in its third edition, is "based on data from the Global Terrorism Database (GTD) which is collected and collated by the National Consortium for the Study of Terrorism and Responses to Terrorism."
The GTI score for a country in a given year is said to be based on unique scoring system to account for the relative impact of terrorism incidents in the year.
"The four factors counted in each country’s yearly score, are: total number of terrorist incidents in a given year; total number of fatalities caused by terrorists in a given year; total number of injuries caused by terrorists in a given year; a measure of the total property damage from terrorist incidents in a given year."