Finally made this list... with number of times I flew from/to each. Connections are counted as one visit.
Germany
MUC Munich Franz Josef Strauss Airport (30+)
FMM Memmingen Allgäu Airport (4)
NUE Nürnberg Albrecht Dürer Airport (2)
FRA Frankfurt Airport (1)
CGN Köln-Bonn Airport (1)
Croatia
ZAG Zagreb Franjo Tuđman Airport (7)
PUY Pula Airport (5)
Sweden
ARN Stockholm-Arlanda Airport (7)
LLA Luleå/Kallax Airport (2)
GOT Göteborg-Landvetter Airport (1)
Portugal
LIS Lisbon Humberto Delgado Airport (7)
FAO Faro Airport (1)
Spain
BCN Barcelona El-Prat Airport (2)
SVQ Seville-San Pablo Airport (2)
TFS Tenerife Sur Reina Sofia Airport (2)
MAD Madrid-Barajas Airport (1)
Brazil
GRU São Paulo-Guarulhos Airport (2)
CGH São Paulo-Congonhas Airport (2)
SDU Rio de Janeiro Santos Dumont Airport (2)
Denmark
CPH Copenhagen-Kastrup Airport (5)
BLL Billund Airport (1)
Italy
VCE Venice Marco Polo Airport (4)
NAP Naples-Capodichino Airport (2)
Norway
OSL Oslo-Gardemoen Airport (2)
EVE Harstad/Narvik-Evenes Airport (1)
SVJ Svolvær-Helle Airport (1)
BOO Bodø Airport (1)
Greece
CFU Corfu Airport Ioannis Kapodistrias (2)
PVK Preveza/Aktion Airport (1)
ATH Athens Airport Eleftherios Venizelos (1)
USA
JFK New York-JFK Airport (4)
Mexico
MEX Mexico City Benito Juárez Airport (2)
Costa Rica
SJO San José Juan Santamaría Airport (2)
Austria
VIE Vienna-Schwechat Airport (2)
Cyprus
PFO Paphos Airport (2)
Poland
GDN Gdańsk Lech Wałęsa Airport (2)
United Kingdom
LHR London Heathrow Airport (2)
Slovenia
LJU Ljubljana Jože Pučnik Airport (2)
France
CDG Paris Charles De Gaulle Airport (2)
Belgium
BRU Brussels-Zaventem Airport (1)
Latvia
RIX Riga Airport (1)
Finland
HEL Helsinki-Vantaa Airport (1)
Switzerland
ZRH Zürich-Kloten Airport (1)