Final answer:
The percentage of Mexicans who owned land in 1910 is not specified in the provided information. Further research on specific data or historical sources is recommended.
Step-by-step explanation:
Unfortunately, the provided information does not specify the percentage of Mexicans who owned land in 1910.
However, it does mention that by the 1880s, californios were relatively landless, indicating a significant decrease in Mexican land ownership over time.
It is important to note that land ownership varied across different regions and socioeconomic groups, and further research on specific data or historical sources can provide more accurate information.