* Self-reporting bias: Surveys on sexual activity rely on self-reporting, which can be inaccurate due to social desirability bias (people might not want to admit to being a virgin or not being a virgin).
* Changing social norms: Sexual attitudes and behaviors change over time and vary significantly across cultures and demographics. A study from one year or one location might not be representative of another.
* Definition of "virginity": The definition of virginity itself can be subjective and varies across individuals and cultures.
* Limited and inconsistent data collection: Large-scale, nationally representative studies on this specific topic are rare. Available data often comes from smaller, targeted studies with limited generalizability.
While some studies might offer estimates, it's crucial to understand that these are estimates with significant margins of error and are likely to vary depending on the methodology and population studied. Therefore, providing a specific percentage would be misleading and inaccurate.