쫌 어려운 문제집인데 해석이 안돼서 ㅠㅠ

도표 맞나틀리나 고르는거거든요? 근데

Tornado fatalities dramatically increased in 1998.

There were 129 tornado-related deaths, which is the most since 1974 when there were more than 350 fatalities.

여기까진 해석이 돼요. 토네이도로 인한 사망자가 1998년에 급격히 증가했고, 129명의 사망자가 났는데 이게 1974년 이래로 최대이다!

맞죠? 근데 그 다음 문장이 좀 이상해요 ㅠ

In only one year since 1974 were there more than 100 deaths and that was in 1984.

only 가 나와서 뒤에 were there으로 도치가 된것까지는 알겠는데

이 문장 해석을 뭐라고 해야 하나요?