
Hiya, what was the source of your episodes and seasons for this show?
https://www.tvmaze.com/shows/17036/la-linea/episodes
Also, all episodes seem to have 1990 as date, but I'm pretty sure I've watched these on TV before that.
Wiki does mention them from 1971-1986 - https://en.wikipedia.org/wiki/La_Linea_(TV_series)
Imdb also mentions year of each episode - https://www.imdb.com/title/tt0406432/episodes?season=1
In some cases they're all just listed as a single season. Like on youtube - https://www.youtube.com/user/LaLineaSeries/videos