That would still be regarded as a fairly young age to die in an advanced part of the western world (as the Netherlands is).
Only six out of 35 still alive is quite striking - that is the sort of statistic I would expect from a place like Russia, or parts of the old eastern Europe where lifestyles were a lot less healthy.
I should have mentioned that 3 died in one car crash, in the late 1960's.
But because the school catchment area these numbers also included many children of the Dutch Reformed Church. No vaccinations, no blood transfusions, etc. Life expectations are always ten year less than the rest of the country.
Plus it must be noted that until 1965 the Netherlands was a very poor country.
The money really started to roll after "Natural Gas" was found in Groningen.
