Certainly my good sir! I sat down and listed all newcomers per iteration and marked down in order of their arrival whether or not they introduced a new IP. Using that number, you can divide by the number of newcomers to find out the % of newcomers who brought with them a new IP.
I had to set the rule of "once a series is confirmed by a character, it can't be counted again). After all, Marth introduced the series but Roy was also in Melee as a clone. So Roy's series was already counted. It makes the calculation a lot cleaner as it removes duplication. I have the tallies below
- Of the 12 newcomers in 64, 10 of them brought a new series (With Luigi and Jigglypuff not adding to the tally)
- For Melee, only 3 newcomers were from a new series (Ice Climbers, Mr Game & Watch, Marth)
- In Brawl, 6 newcomers were from a new series (Olimar, R.O.B, Pit, Snake, Sonic and Wario)
- 3DS/Wii U had the most with a staggering 11 (Bayonetta, Cloud, Duck Hunt Duo, Litte Mac, Mega Man, Mii Fighters, Pac-Man, Ryu, Shulk, Villager and Wii Fit Trainer
- If we exclude DLC, that is 8 out of 15
- Ultimate has 2 right now (Inkling and Simon)
Using that, you can divide by the number of newcomers total to find the rate.
- N64 = 10 / 12 = 83.33%
- Melee = 3 / 13 = 23.08%
- Brawl = 6 / 15 = 40.00%
- 3DS/Wii U = 11 / 19 = 57.89%
- If we exclude DLC, it is 8 / 15 = 53.33%
- Ultimate = 2 / 8 = 25.00%
I do statistics and maths a lot so I am used to this sort of thing. If I excluded the echoes, the rate is higher due to most of them being part of the same series so it distorts the result. But hopefully this makes sense!
EDIT: Per request I have added the option to exclude DLC from 3DS/Wii U