Here at the VDC, we promote having a minimum blood level of 50ng/ml or 125nmol/l. So no we do not consider it “normal”. A blood level of 68 nmol/l will not keep you healthy. At this level and under the incidence of cancer goes up considerably.
Do you take any Vitamin D? At your level you would have to take about 4000iu a day to reach the above higher level. If your level of 68nmol/l is from summer sunshine, then you may want to consider 5000iu a day for winter. This is the daily amount we usually promote.