Data is a key digital economy input and its use is growing rapidly. Large online platforms using data at massive scale operate globally. The data gap between them and the incumbents they disrupt, a barrier to entry in the markets they dominate, affects not only firms but also aggregate innovation, investment and trade. Valuing data is problematic, yet this information is crucial for informed policy decisions on infrastructure and human capital as well as business investment decisions. In this paper we demonstrate a novel sectoral methodology for estimating the economic value of markets for data. Our conservative estimate of the market size for data in the global hospitality industry was US $43.2 billion in 2018, and it has been doubling its size every three years. Our method can provide industry-level and country-level information on data markets. The scale of data flows affects the international division of labor in the digital economy, with important policy implications. With many jurisdictions introducing different data protection and trade regimes, affecting the data gap and data access by market participants, we present a trade typology of countries and discuss their ability to benefit from data value creation.