The given line graph delineates the adjustments in monthly costs of 3 materials in 2014.
Overall, it is readily apparent that the prices of zinc observed an upturn over the period, whereas the opposite was true for the remaining metals. Additionally, nickel underwent the most dramatic shift from the highest percentage to the lowest one.
Regarding Nickel, the figure commenced at 6% in January, which surpassed other materials. It then experienced a notable downswing to 1% in March before remaining unchanged until the next month. Once the rate of change reached the lowest point at -3% in June, the figure experienced a gradual recorvery to 1% in November and was stable till December. With regards to copper, the ratio was second-ranked with 2% in January, after which it witnessed a decline to be the least significant figure in May, at around -0.5%. That then saw constant fluctuations before growing back to nearly the start, at 1.5%.
In terms of zinc, the proportion started at the lowest point in January, at 1%, followed by a slight upturn to 3% in the next month. After that, it dropped to -1% in June and remained essentially unchanged up to October. Finally, the price climbed up to 2% at the end of the period.