get statistics about the research intensity of an industry I want to know how much research is conducted in an industry in order to be able to say Industry X is more research intense than Industry Y.

For industry categorization I use the NACE classificiation.

I know that research intensity per se is an indicator which can be calculated as: 



Ultimately, I want to be able to say, that some industries are more welcome to conduct R&amp;D projects.

Please let me know, if there are any more suitable indicators than R&amp;D intensity. Someone (informally) told me, that R&amp;D intensity is out of fashion, and that IPP (intellectual property products) would be more suitable. However, I am not sure about that.
Perhaps someone with more expertise on the matter can answer your question more directly, but in the mean time:

In the literature on innovation, it is fairly common to use patent data to measure the intensity of innovation activity. 

Here are Aghion et al (2005) on their approach:


  "There is a large literature on measuring innovation intensity, with the most commonly used measures being R&amp;D expenditure and patenting activity. We use the average number of patents taken out by firms in an industry, and to reflect the
  heterogeneous value of patents, we weight each patent by the number of times it has been cited by another patent. These data are generated by matching the NBER patents database to accounting data on firms listed on the London Stock Exchange
  (from Datastream). Our sample includes all firms with names beginning "A" to "L" plus all large R&amp;D firms. After removing firms involved in large mergers or acquisitions and those with missing data, we have an unbalanced panel of 311 firms spanning seventeen two-digit SIC codes over the period 1973-1994. We also have information on citations to and from each patent, which enables us to construct a count of citation-weighted patents. We take the average value of citation-weighted patents of firms within each industry (SIC code) in each year. We do not observe a sufficient number of firms in all industries in all years, so our resulting industry level panel is also unbalanced with 354 industry-year observations."


The latest version of the patent database to which they refer can be viewed here. Aghion et al.'s data is available here.