What is interesting is the comparison of the Czech Republic and Austria. Or between Estonia and Lithuania. Why the disparity? Lithuania and Austria come across at the religious end of the spectrum, whereas Estonia and Czech Republic come across high on the atheist scale.
This is rather interesting that countries in the same "neighborhood" could be so different. It would seem to merit some exploration as to why.
Estonia (along with Latvia) is historically Protestant and Lithuania is historically Catholic. I don't know if that has a bearing on how many of their citizens keep to their ancestral religions.
Bohemia in the 15th century was a hotbed of dissent from the Catholic Church with John Huss and his followers. Catholicism was forcibly re-imposed later by the Habsburgs but even 100 years ago "freethinkers" were more common in the Czech lands than elsewhere. Austria, on the other hand, was willingly Catholic.