That puts things in perspective.
Is it relevant that the graph is in green? Hmmmmmmm!
Seriously, it does put it in perspective. However, back in the 70s you were "home soil" to the root of the terrorists, whereas today, the root of terrorism is in the Middle East. A similar graph based on Iraq, or Afghanistan, might show a similar spike, now. FWIW, had someone managed to get an IED into a football stadium, then you could easily surpass the numbers of the 70s in one event. Or, God forfend, fly a plane into a building.
The significance of the green might be down to the people using religion as an excuse for violence. The IRA, for example, who did like to go for "spectaculars". In all instances American funding and actions have been involved in arming the terrorism.