In each of the years 1995, 1996, 1998, and 1999, variable X grew by 20% year-on-year. But in 1997, X fell by 50%. What might explain this counter-trend fall in 1997?
What might be a better word in place of "counter-trend" here? Googling "counter-trend", it seems like this is somewhat commonly used in investment, but I have not come across it anywhere else. Yet I cannot think of a better word to use in the above context.