Just to provide info for other countries (in Europe, mostly) with lower number of zoos (and in some further post for all rest countries in Europe):
Number of zoos:
Croatia: 35 (of wich 17 mostly are aquaria (+ some terarria), Croatia have long sea coast along Adriatic Sea opposite Italy)
Romania: 30
Belgium: 29
Portugal: 28
Ukraine: 27
Poland: 24 (isn't this too small number, for big country as Poland?)
Hungary: 22
Bulgaria: 20
Ireland: 17
Norway: 17
Estonia: 10
Zoos per 1,000 km2 (as 10x100 km):
Croatia: 0.62
Romania: 0.13
Belgium: 0.95
Portugal: 0.3
Ukraine: 0.05
Poland: 0.08
Hungary: 0.24
Bulgaria: 0.18
Ireland: 0.24
Norway: 0.04
Estonia: 0.22
Citizens/per zoo:
Croatia: 120,000
Romania: 653,000
Belgium: 388,000
Portugal: 371,000
Ukraine: 1,593,000
Poland: 1,603,000
Hungary: 448,000
Bulgaria: 360,000
Ireland: 280,000
Norway: 307,000
Estonia: 130,000
GDP per zoo in billions USD (1 billion = 1,000,000,000):
Croatia: 1.5
Romania: 6.1
Belgium: 15.8
Portugal: 7.3
Ukraine: 3.1
Poland: 21.2 (!)
Hungary: 6.0
Bulgaria: 2.5
Ireland: 15.0
Norway: 22.6 (!)
Estonia: 2.4
Some further post about rest European, and hopefully some non-European countries