Knife stabbings are in the news in the U.K. and the Economist has a quartet of charts to illustrate what's going on.
I'm going to focus on the chart on the bottom right. This shows the trend in hospital admissions due to stabbings in England from 2000 to 2018. The three lines show all ages, and two specific age groups: under 16 and 16-18.
The first edit I made was to spell out all years in four digits. For this chart, numbers like 15 and 18 can be confused with ages.
The next edit corrects an error in the subtitle. The reference year is not 2010 as those three lines don't cross 100. It appears that the reference year is 2000. Another reason to use four-digit years on the horizontal axis is to be consistent with the subtitle.
The next edit removes the black dot which draws attention to itself. The chart though is not about the year 2000, which has the least information since all data have been forced to 100.
The next edit makes the vertical axis easier to interpret. The indices 150, 200, are much better stated as + 50%, + 100%. The red line can be labeled "at 2000 level". One can even remove the subtitle 2000=100 if desired.
Finally, I surmise the message the designer wants to get across is the above-average jump in hospital admissions among children under 16 and 16 to 18. Therefore, the "All" line exists to provide context. Thus, I made it a dashed line pushing it to the background.