Daniel Torres-Salinas et al. have published "Bibliometric and Benchmark Analysis of Gold Open Access in Spain: Big Output and Little Impact" in El Profesional de la Información.
Here's an excerpt:
This bibliometric study analyzes the research output produced by Spain during the 2005-2014 time period in Open Access (OA) journals indexed in Web of Science.. . . . Spain is the second highest ranking European country with gold OA publication output and the fourth highest in Open Access output (9%). . . . Spain's normalized citation impact in Open access (0.72) is lower than the world average and that of the main European countries.