Go to Standard & Poor's Indices

Click on S&P 500 in the 'featured indices' section or search for S&P 500 in the search box in the upper right corner.
Click on Additional Information.
From that menu scroll down and select Monthly and Annual Returns.

You will find monthly and annual total returns back to 1988.
The dividend component of the total return is available for annual S&P returns back to 1988.

Also use Global Financial Data. Click on GFDatabase and Login Anonymously. Search for the keywords S&P 500. Select the S&P 500 Total Return Index or the S&P 500 Composite Price Index.