Is this loss due to a technical problem or some general changes (named-based vhosting instead of IP-based vhosting)? Or just "fluctuation"?
A cursory examination would indicate a mix of factors. Countries with large drops such as fr (-320407), it (-102268) and pt (-19322) still saw increases in their SOA counts. This could be due, as you say, to more name-based virtual hosting, or to more use of NAT, firewalls/private addresses etc. A few countries saw drops in both hosts and SOA records e.g. ru (-88806 hosts, -20199 domains), hu (-18232 hosts, -978 domains). Here we probably have "fluctuations", as zones, for whatever reason, don't get counted this time. It looks like we're seeing the end of the systematic increase in the number of hosts. However, the trend in the number of domains is monotonically upwards; this is probably a better metric of Internet growth than the host count. Regards. Mike