Vancouver, Toronto and Calgary are numbers 3, 4 and 5 on a list of the world's most livable cities, rankings unchanged from last year despite growing global instability affecting other nations' positions.

The Economist Intelligence Unit released its annual livability index on Thursday, and the top five countries match last year's list: Melbourne, Australia, at number 1, followed by Vienna, Vancouver and Toronto, with Calgary and Adelaide, Australia, tied for fifth.

The index measures 30 factors that fall under five categories: security, health care, education, infrastructure, and culture and the environment to assign a score out of 100.

Vancouver scored 97.3, Toronto 97.2, and Calgary 96.6.

The report noted a strong correlation between the cities at the very top of the index.

"Those that score best tend to be mid-sized cities in wealthier countries with a relatively low population density," the report said.

"These can foster a range of recreational activities without leading to high crime levels or overburdened infrastructure."

Six of the top 10 cities are in Canada and Australia, the report went on, which have a population density of 3.9 and 3.1 people per square kilometre, respectively.

The report also noted that violent crime may appear to be on the rise in some of the top cities, but the statistics tell another story.

In Vancouver, for example, the murder rate increased in 2014 after a record-low 2013. But those two years "were still the years with the lowest national murder rates in Canada since 1966," the report said.

Toronto has kept its number 4 ranking on the EIU's livability index. (CBC )

All three Canadian cities received top marks for health care and education, but their scores varied under the other categories.

While Toronto and Calgary received a top mark of 100 for stability, Vancouver received 95. And while Vancouver received a top mark for culture and environment, Toronto's score was 97.2 and Calgary's was 89.1.

On infrastructure, none of the three cities received a perfect score. Calgary received 96.4, Vancouver received 92.9, and Toronto 89.3.

Global instability growing

The index ranks 140 countries, and many of the position changes this year can be attributed to growing instability around the world, the report said.

Sydney, Australia, for example, fell four places to move out of the Top 10, a drop that can be attributed to a "heightened perceived threat of terrorism," the report said. This allowed Hamburg, Germany, to move up to tenth place, but also led to negative ranking changes for Frankfurt and Berlin, which "have experienced declines in stability," the report said.

The impact of declining stability is particularly noticeable when looking at the last five years. The global average livability score has fallen 0.9 per cent to 74.8 per cent over the past five years, the report said. The average global stability score has fallen by 2.4 per cent over the past five years, from 73.7 per cent in 2012 to 71.3 per cent now.

"Over five years, 96 of the 140 cities surveyed have seen some change in overall livability scores," the report said. "Of these cities, 71 have seen declines in livability, up from 52 just six months ago."

While big international cities such as New York, London, Paris and Tokyo might be expected near the top of the list, they can be "victims of their own success," the report said. They are prestigious cities with a lot of recreational activity, but also have higher crime rates, congestion and public transportation problems.

Other U.S. cities have seen declines in scores, in part due to police shootings of black men and deaths in police custody, and the resulting civil unrest, the report said.

As well, Paris saw a "sharp decline" in its ranking due to the number of recent terror attacks in that city and across France over the past three years.

"Although the most livable cities in the world remain largely unchanged, there has been movement within the top tier of livability," the report said. "Of the 65 cities with scores of 80 or more, 17 have seen a change in score in the past 12 months. As global instability grows, these movements have been overwhelmingly negative, with no city in the top tier registering a score improvement."

Meanwhile, declines were particularly evident in cities at the bottom of the index, where civil war and terrorism are contributing to instability. Ranked at the bottom, at 140, is Damascus, Syria, followed by Tripoli, Libya; Lagos, Nigeria; Dhaka, Bangladesh; and Port Moresby, Papua New Guinea.