They didn't win any between 1776 and 1889 for instance.There was probably over 100 years where Slovenia and Denmark didn't win 6 between them in total.
Volta a Catalunya was held for the first time in 1911, and if we count 101 years from then, although there obviously wasn't a World Tour at the time, and the current WT races haven't all been the biggest races on the calendar during their entire existence either, then I think we're only on 3 victories during that period (T-A 1987 and 92, Romandie 2010). Since 2011, they've won another 24 (if I've counted them correctly).