I'm confused then i assumed that the rarity column contained rarity values taken from the atarimania web site or another source
Rarity ratings are very volatile. Atarimania though a good baseline hasn’t been updated in the last 7+ years that I’m aware of. This means when more carts are found, i.e. the warehouses in South America, then rarity should change. I used Atarimania, and several other lists, and combined that to my over 10 years of collecting. Cartridges are like gold, the prices go through what appears to me to be a 5-7 year cycle. Currently, outside of some very hard to get carts, we are in a slump. Prices are at an all time low. Great time to buy, not so good to sell in my opinion.
But again, rarity should be taken with a grain of salt. The real value is in the demand and that is where it changes often. My rarity indicators are a snapshot of today based on those lists, user input, posting data, and my experience (I have something like 330 individual unique cartridges (minus label variations, etc)).