Large sums have been allocated to bike infrastructure since the early/mid-70's.
Love the vagueness of your reply. My point that much of the separated path build out occurred later remains:
Since 1990, the total length of cycle paths has increased to almost 19,000 km, generally speaking double the length in 1980. (The Netherlands has around 108,000 km paved and asphalted roads, including 2200 km of expressways). Besides cycle paths, there were also investments in round-abouts, reconstructions of junctions and pedestrian/cyclist crossings, cycle tunnels and bridges and parking facilities for cyclists; totalling
an estimated 1.5 billion guilders.
Quote from:
The autumn of the Bicycle Master Plan: after the plans, the products.
Ton Welleman
Dutch Ministry of Transport, Public Works and Water Management, The Hague, the Netherlands