Meh, these monthly fluctuations are dominated by noise, especially when expressed as "percentage of total sales". You get both the variation in EV sales and in ICE sales influencing.
Look at the trends in the absolute numbers over time:
It looks like total yearly sales for all types in Norway is ~150k/year. 6 months into the year, electric is at ~33k total. However you look at it, this is a tiny market.
Look at the trends in the absolute numbers over time:
https://elbilstatistikk.no/