Final answer:
The provided data does not directly indicate the current majority level of health literacy among adults. However, historical literacy trends and issues presented imply that while overall literacy has improved dramatically since the 1870s, specific adult groups still face significant challenges, and overall health literacy awareness remains necessary.
Step-by-step explanation:
The majority of adults have what level of health literacy? The data and studies provided do not include specific percentages that directly answer this question regarding the current majority level of health literacy among adults. However, given the context provided, we can infer that there is a significant portion of adults who may face challenges with health literacy, as evidenced by the fact that adult literacy levels for specific groups such as adults with disabilities, prisoners, and adult migrants have seen no improvement in 60% of the countries reporting this information to GRALE 5. Additionally, 24% of the countries reported a decline in adult literacy in rural populations and the same percentage in older adult literacy.
More broadly speaking, the change in literacy over time has been remarkable. In 1870, only 19% of the world's population was literate, compared to 87% in 2020. This suggests an overall improvement in literacy, which is a component of health literacy. Nonetheless, despite the increase in women's adult literacy rates, the need for greater awareness and improvements in adult literacy remains clear.
An increased emphasis on literacy can lead to a better understanding of health information and thus, better health literacy among adults. This would likely reflect in more adults having higher levels of health literacy. Moreover, understanding printed information has links with literacy rates, as a report from 2014 pointed out that 69% of people had read at least one printed book in the past year. Studies also suggest that reading on paper might aid comprehension compared to e-books.