In the context of this series of interconnected finance-related queries and the additional information provided by the pretext, table data, and posttext from a company's financial filings, please provide a response to the final question. This may require extracting information from the context and performing mathematical calculations. Please take into account the information provided in the preceding questions and their answers when formulating your response:
Context: 2 0 0 8 a n n u a l r e p o r t stock performance graph the following graph sets forth the performance of our series a common , series b common stock , and series c common stock for the period september 18 , 2008 through december 31 , 2008 as compared with the performance of the standard and poor 2019s 500 index and a peer group index which consists of the walt disney company , time warner inc. , cbs corporation class b common stock , viacom , inc . class b common stock , news corporation class a common stock , and scripps network interactive , inc . the graph assumes $ 100 originally invested on september 18 , 2006 and that all subsequent dividends were reinvested in additional shares . september 18 , september 30 , december 31 , 2008 2008 2008 . <table class='wikitable'><tr><td>1</td><td></td><td>september 18 2008</td><td>september 30 2008</td><td>december 31 2008</td></tr><tr><td>2</td><td>disca</td><td>$ 100.00</td><td>$ 103.19</td><td>$ 102.53</td></tr><tr><td>3</td><td>discb</td><td>$ 100.00</td><td>$ 105.54</td><td>$ 78.53</td></tr><tr><td>4</td><td>disck</td><td>$ 100.00</td><td>$ 88.50</td><td>$ 83.69</td></tr><tr><td>5</td><td>s&p 500</td><td>$ 100.00</td><td>$ 96.54</td><td>$ 74.86</td></tr><tr><td>6</td><td>peer group</td><td>$ 100.00</td><td>$ 92.67</td><td>$ 68.79</td></tr></table> s&p 500 peer group .
Conversations: 
q0: from september 30 to december 31 of 2008, what was the decline in the performance price of the s&p 500? 21.68
Question: and what was that price in december 31?
Answer: