Looking at the graphs, it can be seen that Marvel search trends across all three countries peek during the week of April 29th - May 5th, 2018. This is most likely due to the fact the Avengers: Infinity War (Marvel's biggest film to date) was released in theaters just two days prior, on April 27th. Additionally, smaller spikes can be seen that correspond with the release of different Marvel movie trailers over the past year. For example, the Captain Marvel trailer was released recently on September 18th, 2018; Marvel trends in the US, UK and China experienced spikes the week of September 16th - 22nd.
Something interesting seen in the DC results is that there does not seem to be as much of a correlation between the search trends and movie releases. Justice League, DC's main competition to Marvel's Avengers, was released November 15th, 2017 (November 17th in China); Across all three countries, there seems to be no significant spikes in search trends during that week, November 12th - 18th. The same goes for trailers, as there were no significant spikes when DC's Shazam trailer released on July 21st, 2018.
The correlation of movie/trailer releases and search trends of Marvel compared to DC signify that Marvel's movies currently have a greater impact on the industry and the public's interest in the company itself. There are numbers to back this up as well. While Avengers: Infinity War grossed $2,046,548,594 worldwide, Justice League grossed a mere $657,924,295 worldwide; Avengers made Justice League's worldwide grossing in it's first 4 days of release. Marvel's search trend spikes correlating with their movie releases and high grossing amounts show there is a greater amount of excitement surrounding their movies compared to DC. This could be do to the positive reviews that the movie received compared to Justice League's mediocre reviews (as you can see by comparing The Atlantic's reviews of the two movies in the overview page), or because mainstream audiences are more familiar with Marvel movies, as they have been made since 2008's Iron Man.In conclusion, while search trends prove DC to be more popular than Marvel overall, people just are not as interested in DC's movies as they are in Marvel's. It will be interesting to see if this will ever change in the future.