Final answer:
The precise ratio or percent value of products with generic EPDs cannot be given without specific context, as it varies by product category and EPD standard.
Step-by-step explanation:
The question relates to the valuation of products with industry-wide Environmental Product Declarations (EPDs). An industry-wide (generic) EPD reflects the average environmental impact for a product category rather than for a specific manufacturer's product. However, without the specific context or standards being referenced, it's not possible to provide a numerical ratio or percent that such products are valued at. Often, these values depend on the product category and the standard under which the EPD is developed. Generally, products with specific EPDs can be considered to have a higher value in green building assessment systems compared to products that only have generic EPDs, because they provide more detailed environmental impact data.