The Nikkei 225 recently reached a 21 year high according to The Economist in the October 12, 2017 issue.
The graph is a bit misleading. Because the vertical axis starts at 5000 rather than 0, the index may appear to have tripled since its low rather than doubled.
It is certainly okay to start an axis at a value other than zero for a line graph. But in this case, there is no downside in starting at zero. And our initial impression would be more accurate.
There is another concern: What is special about 1996? Was it a high point?
Including the high point in 1989 would have made a more complete, if longer story.