The field of visual Industrial Anomaly Detection (IAD) has brought forth many new semi-supervised learning methods in recent years. At the same time, there have been few new datasets for benchmarking the methods. The most popular dataset is MVTec-AD dataset, because of its diversity of categories and availability of industrial objects. But many methods already achieve AUROC scores of more than 99 % on the MVTec-AD dataset. The defects of the categories that the dataset provides appear to be easily detectable. Furthermore, there is no existing approach to statistically describe the defects that need to be found in IAD datasets. This paper presents a new dataset for visual industrial anomaly detection and a novel approach for Anomaly Detection Dataset Difficulty assessment with the AD3 score. The new dataset named VIADUCT contains 49 categories and 10,986 high resolution images from eleven different sectors. Through the support of several manufacturing companies, numerous real inspection problems are presented through the dataset. It contains a large number of different defects with detailed pixel-wise annotations. The VIADUCT dataset is compared with other state of the art datasets to underline its added value. Therefore, we provide an overview for each dataset regarding the number of categories, images, defect categories and defects. In addition to these obvious comparisons the defects of the datasets are described with the AD3 score. This novel score is used to analyze the size of the defects and the similarity between the defect and its corresponding object. Using seven selected methods from industrial anomaly detection, a benchmark is performed on the new dataset, showing that there is still potential for improvement. It is shown that the VIADUCT dataset is the largest dataset in the field of image-based industrial anomaly detection. In addition to its very small defects which are hard to recognize, the dataset also offers the greatest variance of possible defects and the most defect classes. Describing the datasets with AD3 score it can be found that VIADUCT dataset have the smallest and most inconspicuous defects. With the AD3 score we are able to create a-priori knowledge for every single defect in IAD datasets. The AD3 score correlates with the results of the IAD method benchmark, showing that it can be used to estimate defect detection difficulty. In the future, new objects can be assessed to see whether defects can be recognized using IAD methods before an energy-intensive benchmark is performed. The simple calculation of the AD3 score generates valuable a-priori knowledge and can save resources.