Once again, the world is mourning dozens killed in an apparent terror attack in the heart of Europe.The trio of explosions in Brussels — two at the airport and one at a metro station — came just four months after 130 people were killed in a series of coordinated attacks across Paris. More than 30 people are believed to be dead following Tuesday's violence.While incidents like the ones in Brussels and Paris "reveal that Europe is vulnerable to deadly terrorist attacks," terrorism in the continent overall remains lower than in the 1970s and 1980s, according to Erik Cleven , PhD, an assistant professor of politics at Saint Anselm College in New Hampshire. And sadly, the tragedy in Brussels is far from the only case in which dozens have died from suspected terror attacks in recent weeks.As Cleven notes in a statement released by the college, "The vast majority of attacks today, and fatalities resulting from terrorist attacks, are still experienced in five countries, namely Afghanistan, Pakistan, Syria, Iraq, and Nigeria."While they are often just as, if not more, deadly than the assaults in Brussels, these attacks across the Middle East and Africa don't always garner the same level of media coverage and international response. Some people online have pointed out that gap in attention, calling on the world to remember all victims of terrorism in the wake of the Brussels attack.