Hi DipLim,
This is a good visualization. Solid observation and justification as to the limitation of the colour gradient. A potential improvement could be to look into using stepped colours as opposed to using a colour gradient.
Having a low amount of step values will make any large changes more noticeably visually.
As an example, Canada has almost double the value of Italy on the chart, but it’s very difficult to see that due to the lob-sided nature of the colour gradient
Despite those grips, your visualization conveys it’s overall meaning clearly enough!