Do flight costs to a city hosting the Olympics generally increase around the event?

While I unfortunately haven't been able to find any comprehensive, hard statistics regarding this, and my personal guess would be an increase, I have found no consistent, conclusive evidence to back up that guess. Instead, I have found examples of it going both ways.

Regarding the 2016 Rio Olympics, according to The Telegraph, flight prices from the UK and Austria to Rio increased by 48% and 74% respectively, compared to the year before. However, the flights from Switzerland and Italy dropped by 1% and 18% respectively for the same comparison.

Regarding the 2012 London Olympics CBC News noted that (emphasis mine):

[Flight] prices are largely unchanged from the same dates last year, in part because mega-events like the Olympics can scare off as many visitors as they attract, [Travel Agent Chris March] said.

"It can work both ways. It entices people to go there and be a part of such an amazing event. But also, people are aware that it's a big city and [with] an extra 3 million people on top of that, it's going to be a busy time."

Before the 2008 Beijing olympics, The Independent noted (emphasis mine):

Air fares have also been cut. In February, the cost of return flights to Beijing during the Olympics started at around £1,200 with Air China and £1,500 with British Airways. Emirates is now offering return flights during the Games from as little as £497, Air China from £503 and BA from £972.