In the past decades the use of Esperanto has increased more and more. This is also shown by the fact that there are now at least a hundred people for whom Esperanto has become the main language, the language they use more than their other languages.
So often and so long Esperanto is used e.g. by employees of Esperanto organizations, many of whom also speak Esperanto at home with their partner and their children. Others use Esperanto a lot in their free time, possibly alongside part-time work or after retirement. Some also work as volunteers in an Esperanto organization or in Internet projects.
In a survey on Facebook (group "Esperanto") between 17 July 2018 and 4 May 2019, a total of 88 people reported that they had used Esperanto in more than 50 % of their time in the past twelve months; in the first three weeks, until 11 August 2018, 57 people chose Esperanto, 76 people until the end of August.
The question was (ütranslated from Esperanto): In what proportion of the time of year do you use Esperanto? (Example: Maybe you work in a national language, use Esperanto at home, spend four weeks on holiday in an Esperanto environment. So maybe during one working day you get 30 % Esperanto, on weekends 80 %; on average during one week maybe 5x30+2x80=310; 310/7 ~ 45 % Esperanto. In the year 11x45+1x100 ~ 600; 600/12 ~ 50 %).
ADDITION. For precision and explanation:
In which part of the last 12 months did you use Esperanto?
As of 4 May, in addition to the 88 people who stated that they used Esperanto in more than 50% of their time, another 71 people reported that they used Esperanto in 26 to 50% of their time. According to the survey, 35 people use Esperanto in 11 to 25 % of their time. 224 persons informed that they use Esperanto in between 0 to 10 % of their time. A total of 418 people participated. It should be noted that the survey is open, not anonymous - every Facebook user can view the list of people for each opportunity.
It can be assumed that, in addition to the people who took part in the survey, there are other people, on Facebook or outside, for whom Esperanto has become the main language. Of course, there may also be inaccurate information or mistakes, but this is probably rare. Overall, it can therefore be assumed that the number of persons with Esperanto as their main language is currently in the range between one hundred and several hundred persons.
As examples of persons with Esperanto as their main language, two fathers from children speaking Esperanto (from the author's circle of acquaintances) are presented. Both have been involved in Esperanto projects for many years, which are strongly connected to the Internet; both do not do any other work. The partner of one (the other currently has no partner) and a very large proportion of the friends and acquaintances of the two speak Esperanto; contact with them is maintained personally and via the Internet. Both take part several times a year in Esperanto events, which often last a week. The contacts to people who do not speak Esperanto are on the one hand part of the family, on the other hand the shopping; nowadays shopping takes place practically without words (partly via automatic cash registers); the contact to the rest of the family takes place only every few weeks (or in the case of the other even less, because he lives in another country). The two persons have indicated an Esperanto share in their communication of 85 % and 95 % respectively.
Louis F. v. Wunsch-Rolshoven
(Translated with the help of http://www.DeepL.com/Translator)