A Pseudo-scientific, non-definitive and completely biased ranking of every one of AR Rahman's Tamil Albums

I was listening to a  Rahman station on of the new-fangled streaming services when "Netru Illatha Matram" came up and it struck me. Pudhiya Mugam was probably one of ARR's best albums.The album came out in 1993. 25 freaking years ago.  I am not sure if I this is because I am getting old, but, I also had the feeling that the albums from the 90's were better than the later years. Since I had a couple of hours on my hand I decided to put the theories to test. I needed to score and rank all of ARR's albums. At least the tamil ones.  So, here is what I did

1. I pulled a list of Tamil albums from Wikipedia. I included only Original Tamil movie sound tracks. This meant that Dil Se and Guru were out even though they were dubbed in to Tamil whereas "Manasukkul Oru Puyal"(ugh!) from Star was included even though the song was composed for Thakshak(Boondon Se Baatein). This included 68 albums from Roja to Kaatru Veliyidai
2. I then went through each album and identified songs that I absolutely loved in each album and songs that I would never  voluntarily agree to listen to ever again.  Since this is my ranking and the fact that only my opinion really matters, this was purely based on my personal likes/dislikes. I am sure there are millions of people who like Rukkumani Rukkumani from Roja. But, I detest the heck out of that song. I also think that Nee than En Desia Geetham was brilliant to which no one I know agrees with. So,there! Any song that does not fall in to the two buckets is a so-so song. I hate theme songs(If there are no words, it is not a song! Sorry. But I am ready to fight people on this), so they all made it in to this bucket. 
3. I noticed that there was  gap between 2003 and 2005 when there were not many albums I would ever listen to again voluntarily
4. The next step was to assign scores for each album. Again, I made up the rules. I wanted to compare apples to apples. So, I divided the count of great songs in an album by the number of songs in that album. This would tell me what fraction of the album was truly great. from this I subtracted the fraction of the album that I considered bad. When I realized that there were a lot of so-so albums in the 2000's I decided to penalize the so-so songs(and the theme songs). Surely, a so-so song is not as bad as a "Rukkumani" song. So, I assigned a .25 weight to the so-so fraction and it would be a negative. Since I did not want to deal with decimals, I multiplied the total by 100. So, the score for each album turned out to be  

Album Score= ((# Great songs-(0.25* #so-so songs)- #horrible songs)/(#songs in the album))* 100

So, without much ado(except for a brief drum roll), the best albums

Year	Tamil	#	Best Song	Worst Song	Yay!	So-so	Ugh	Score
1995	Indira	6	Thoda Thoda Malardhadhenna		5	1	0	79
2000	Alaipayuthey	9	Evano Oruvan	September Maadham	8	0	1	78
1993	Pudhiya Mugam	7	Netru Illadha Matram		5	2	0	64
2016	Achcham Yenbadhu Madamaiyada	5	Avalum Naanum	Showkali	4	0	1	60
2017	Kaatru Veliyidai	6	Nallai Allai		4	2	0	58

There! Puthiya Mugam is the third best. Vindicated! Indira was the best? Seriously! Which idiot came up with this list? Oh? okay, then! Duet was no 21because of the sheer size of the album-14 songs.
Next, Lets look at the worst ever albums
Year   Movie                        #      Best Song                Worst song         Great!   So-So Ugh! Score
1996   Kadhal Desam          6      Mustafa Mustafa      Hello Doctor            1          2            3   -42
1994   Karuththamma          7     Kaadu Potta Kaadu   Thenmerku              0          5            2   -46
1999   Jodi                           9                                       Oru Poiyavadhu       0          4            5   -67
2002   Alli Arjuna               5                                        Sollayo Solaikilli     0          1           4    -85
1999   Kadhalar Dhinam     7 Enna Vilaiyazhagae       Kadhalenum            0          1            6   -89

 I was surprised that Kathal Desam was in the bottom 5. Alli Arjuna and Kadhalar Dhinam are the worst! I love some of the Alli Arjuna songs in their Hindi avatars, but the lyrics in Tamil are truly Ugh!(I mean.... Sollaya Solai kili, really?) There is no such redemption for Kadhalar Dhinam. It doesn't help the fact that most of the songs were pictured on Kunal(RIP).

Here is another amazing insight. Are you ready? Here are the scores by decade

Decade        # Movies     Total Score  Average Score
1990's           32               119              3.72
2000's           23              -192             -8.35
2010's           13               198              15.23

Who would have thunk it? on an average the albums that came out 2010 and later are better! The worst albums in the decade were Kochadiayaan, Lingaa and 24 which were not bad. The problem was that the albums were not memorable either. On the other hand the 2000s started strong with Alaipayuthe, Kandukondein, Rhythm and Tenali and ended with a whimper with ATM and Sakkarakatti

Here is the entire spreadsheet .