I dont know if anyone wants to know this, but throughout the time of League, there has been alot of 
, but not alot of 
. Also, i will be updating this every week. Thoughts?
Ashe existed at the start of the game.
Yorick can still be considered relatively new for someone who's been playing that long.
IIRC Riot stopped putting Yorick on free week in season 2 because of the common "Yorick has no counter" mentality.
Thank you for compiling this data, and I hope you're able to keep up with updating it. I'm trying to plan ahead a few months as to when certain champs I might want will go on sale. But many of those champs, I haven't had a chance to play. So having some kind of data on how often those champs have been free helps give me a clue as to whether I'm likely to get a chance to try them on free week before the next time they go on sale.
Think you could add a formula that shows roughly how many weeks go by on average between free week appearances for each champ? The Grand Total column is not as meaningful when comparing a champ that has been out since the beginning to a champ that has only been out a year.
Edit: I have some ideas on how to implement this without the upkeep being too difficult. Let me know if you want to hear them.
Ashe is pretty obviously a frequent free rotation participant. She is in the free rotation every 4.1 weeks. Unsurprisingly, Sivir (4.3 weeks) and Annie (5.3) are pretty common. However, Kalista is actually the 3rd most common free week champ at just 4.8 weeks between appearances.
Certain support champs are also very frequently in the rotation: Morgana (tied for 5th at 5.6), Taric (also 5.6), Soraka (tied for 7th at 5.7), Zilean (also 5.7), and Braum (10th at 5.8).
The 10 free champs tend to follow the meta with 2 top, 2 mid, 2 ADC, 2 support and 2 jungle. There are fewer ADC champs and Support champs in the game than the other 3 roles, so it makes sense that the champs that appear the most often in free rotation are ADCs and Support.
Meanwhile, at the other end of the spectrum, people have already come to realize that Yorick, Poppy, Alistar and Tristana aren't going to be in the rotation. Those 4 aside, what champs appear the least often in the free rotation? Shaco - 23.6 weeks between appearances Evelynn - 23.5 Rumble - 19.2 Jayce - 18.5 Swain - 18.2
The "average" time between appearances for all champs is around 10.6 weeks.
Most common ADCs: Ashe (4.1); Sivir (4.3) Least common ADCs: Draaaaaaven (11.7), Twitch (11.4) Most common junglers: Amumu (6.6), Fiddlesticks (6.8) Least common junglers: Shaco (23.6), Evelynn (23.5) Most common mids: Heimerdinger (6.4), Veigar (6.8) Least common mids: LeBlanc (18.2), Syndra (17.4) Most common supports: Annie (5.3), Morgana (5.6) Least common supports: Karma (12.4), Nami (9.2) Most common tops: Cho'Gath (5.8), Ryze (6.1) Least common tops: Rumble (19.2), Jayce (18.5)
