What are the chances?

I am a statistics man. I am also a novice writer. What are the chances of a new writer, with about 4 to 5 screenplays completed, and does this part-time, to actually have a shot at making low six figures (approx. $150-$250K) from one of them? Like how many screenwriters are actually out there doing this? 3 million? 10 million? And how many actually get bought? You know what I am trying to say? Like if there were 200,000 works written and submitted this year and only 200 are bought, then that's .1% of the group and if you submit 20 of those screenplays then maybe you have a 10% chance of getting lucky, you know what I am getting at? I love movies and watch them all the time, but it seems that the only ones I see made are the known screen writers that already have a few under their belt. The same for all the ones sold shown in Script Sales? So is it easier to win the lotto or break in with a work?