I think you may need to watch the new contracts for a while to see how often they are adding them. I can tell you that in October 2018 I was interested in listing 5004091. In November that year I offered on 5004197. We now seem to be up to 5007xxx. No idea if that helps in the slightest! It seems to be about 3000 contracts advertised in 20 months (150 a month), but I have never looked at patterns or trends with this. I was only looking at the resort I was interested in and the prices for that!