Ragnhild was only on the charts in Norway for five years; nevertheless, it managed to rank at #2 for one year. It ranked at #5 in 1930 (behind Bjørg, Inger, Solveig and Gerd) and was out of the top 10 by 1935.
In Norway 'Ragnhild' can be pronounced in two ways - either /'ragn-hild/ or /'raŋn-(h)ild/. Grammatically, the former pronunciation is the right one, but people tend to be lazy so many favour the latter - the latter is certainly the easiest to pronounce.
In Denmark we pronounce this name as 'roun-hill'. I always thought it had something to do with ravens as the Danish word for raven is ravn (pronounced like round without the d - aka the same sound as ragn in Ragnhild).I think it's a strong name!