Hollywood's decline!

So, have you guys/girls seen this picture going around the Internet about the decline of Hollywood over the past 4 decades 1981,1991, 2001 & 2011. Well I read through the picture about 15 times tonight, an it seriously got to me. If you haven't seen the picture I will break it down for you.

Top 10 Films of each year;
1981:
1 - Raiders Of The Lost Ark
2 - On Golden Pond
3 - Superman II
4 - Arthur
5 - Stripes
6 - The Cannonball Run
7 - Chariots Of Fire
8 - For Your Eyes Only
9 - The Four Season
10 - Time Bandits

1991:
1 - Terminator 2
2 - Robin Hood
3 - Beauty And The Beast
4 - The Silence Of The Lambs
5 - City Slickers
6 - Hook
7 - The Addams Family
8 - Sleeping With The Enemy
9 - Father Of The Bride
10 - The Naked Gun 2 1/2

2001:
1 - Harry Potter 1: And The Philoshper's Stone
2 - Lord Of The Rings: The Fellowship Of The Ring
3 - Shrek
4 - Monsters Inc
5 - Rush Hour 2
6 - The Mummy Returns
7 - Pearl Harbour
8 - Ocean's Eleven
9 - Jurassic Park III
10 - Planet Of The Apes

2011:
1 - Harry Potter 8: And The Deathly Hallow Part 2
2 - Transformers 3: Dark Of The Moon
3 - The Twilight Saga 4: Breaking Dawn Part 1
4 - The Hangover Part 2
5 - Pirates Of The Caribbean 4: On Stranger Tides
6 - Fast Five
7 - Cars 2
8 - Thor
9 - Rise Of The Planet Of The Apes
10 - Captain America

Above is a list of the top 10 grossing films in the US each year '81, '91, '01 and '11. RED = Sequel, BLUE = Adaptation and Green = Original. Look at that back in 1981 there was 7 original films in the top 10 grossing films, put that up next to 2011 an there was not a single original film in the top 10 what I get from this is that Hollywood is getting lazy! The only truly original film that made the top 15 grossing films was "Bridesmaids" which only made it in at number 14.

What does this mean for the originality in Hollywood? Is it declining as most people I know say? Is there a lack of original screen writers working? Or are the studios just getting greedy an want to make money before they make a original film?