date released                        polling institute social democratic       socialist green - communist democratic and social centre           lead
0      october 6 , 1991                         election results   50.6% 135 seats  29.1% 72 seats     8.8% 17 seats                 4.4% 5 seats          21.5%
1      october 6 , 1991   exit poll - rtp1 universidade católica     48.0% - 51.9%   28.5% - 31.5%      7.5% - 10.0%                  4.5% - 5.5%  19.5% - 20.4%
2      october 6 , 1991  exit poll - tsf / expresso euroexpansão     45.8% - 50.2%   29.8% - 33.9%       6.8% - 9.1%                  3.7% - 5.5%  16.0% - 16.3%
3      october 6 , 1991            exit poll - antena1 euroteste     47.0% - 50.0%   31.0% - 34.0%      7.5% - 10.0%                  4.0% - 5.0%          16.0%
4   september 28 , 1991                                euroteste             47.3%           35.5%              8.5%                         4.1%          11.8%
5   september 28 , 1991                                euroteste             46.0%           37.0%              9.7%                         3.9%           9.0%
6   september 28 , 1991                             euroexpansão             44.0%           33.0%              9.0%                         6.0%          11.0%
7   september 27 , 1991                                 marktest             43.1%           32.8%              7.7%                         4.6%          10.3%
8   september 27 , 1991                               pluriteste             41.2%           34.7%              8.4%                         8.1%           6.5%
9   september 20 , 1991                                euroteste             45.6%           35.5%             10.0%                         4.4%          10.1%
10  september 20 , 1991                                 marktest             41.9%           31.9%              7.3%                         4.4%          10.0%
11  september 16 , 1991                               pluriteste             39.2%           26.6%              6.2%                         6.0%          12.6%
12  september 16 , 1991                                euroteste             45.1%           34.5%             10.2%                         5.2%          10.6%
13  september 14 , 1991                                    norma             45.0%           37.5%             11.2%                         3.5%           7.5%
14     august 28 , 1991                  euroexpansão / marktest             35.3%           36.8%              8.7%                         4.9%           1.5%
15      august 4 , 1991                           euroteste / jn             47.5%           37.8%             12.3%                         8.2%           7.7%
16       july 19 , 1987                            1987 election   50.2% 148 seats  22.2% 60 seats    12.1% 31 seats                 4.4% 4 seats          28.0%

Table as JSON:
{"date released":{"0":"october 6 , 1991","1":"october 6 , 1991","2":"october 6 , 1991","3":"october 6 , 1991","4":"september 28 , 1991","5":"september 28 , 1991","6":"september 28 , 1991","7":"september 27 , 1991","8":"september 27 , 1991","9":"september 20 , 1991","10":"september 20 , 1991","11":"september 16 , 1991","12":"september 16 , 1991","13":"september 14 , 1991","14":"august 28 , 1991","15":"august 4 , 1991","16":"july 19 , 1987"},"polling institute":{"0":"election results","1":"exit poll - rtp1 universidade católica","2":"exit poll - tsf \/ expresso euroexpansão","3":"exit poll - antena1 euroteste","4":"euroteste","5":"euroteste","6":"euroexpansão","7":"marktest","8":"pluriteste","9":"euroteste","10":"marktest","11":"pluriteste","12":"euroteste","13":"norma","14":"euroexpansão \/ marktest","15":"euroteste \/ jn","16":"1987 election"},"social democratic":{"0":"50.6% 135 seats","1":"48.0% - 51.9%","2":"45.8% - 50.2%","3":"47.0% - 50.0%","4":"47.3%","5":"46.0%","6":"44.0%","7":"43.1%","8":"41.2%","9":"45.6%","10":"41.9%","11":"39.2%","12":"45.1%","13":"45.0%","14":"35.3%","15":"47.5%","16":"50.2% 148 seats"},"socialist":{"0":"29.1% 72 seats","1":"28.5% - 31.5%","2":"29.8% - 33.9%","3":"31.0% - 34.0%","4":"35.5%","5":"37.0%","6":"33.0%","7":"32.8%","8":"34.7%","9":"35.5%","10":"31.9%","11":"26.6%","12":"34.5%","13":"37.5%","14":"36.8%","15":"37.8%","16":"22.2% 60 seats"},"green - communist":{"0":"8.8% 17 seats","1":"7.5% - 10.0%","2":"6.8% - 9.1%","3":"7.5% - 10.0%","4":"8.5%","5":"9.7%","6":"9.0%","7":"7.7%","8":"8.4%","9":"10.0%","10":"7.3%","11":"6.2%","12":"10.2%","13":"11.2%","14":"8.7%","15":"12.3%","16":"12.1% 31 seats"},"democratic and social centre":{"0":"4.4% 5 seats","1":"4.5% - 5.5%","2":"3.7% - 5.5%","3":"4.0% - 5.0%","4":"4.1%","5":"3.9%","6":"6.0%","7":"4.6%","8":"8.1%","9":"4.4%","10":"4.4%","11":"6.0%","12":"5.2%","13":"3.5%","14":"4.9%","15":"8.2%","16":"4.4% 4 seats"},"lead":{"0":"21.5%","1":"19.5% - 20.4%","2":"16.0% - 16.3%","3":"16.0%","4":"11.8%","5":"9.0%","6":"11.0%","7":"10.3%","8":"6.5%","9":"10.1%","10":"10.0%","11":"12.6%","12":"10.6%","13":"7.5%","14":"1.5%","15":"7.7%","16":"28.0%"}}